We write about a variety of platforms here at Lifehacker, and even if you're perfectly happy with what you're using, nothing makes you feel more appreciative (not to mention knowledgeable) than trying something new. Take some of your free time this weekend and give a new OS a shot.

Windows

Windows gets a bad rap these days, but it's actually a great operating system. If you haven't tried out Windows 7 yet (or if you haven't used it in a while), check out our master list of Windows 7 shortcuts, and get to know big features like the taskbar and the Windows 7 libraries. Of course, it has a lot of really underhyped features that rock, too, not to mention lots of clever hidden tricks.

Of course, if you've been using Windows 7 for the past few years, you still have some new things to try out in the awesome, upcoming Windows 8. You can download the developer preview now, and install it or run it in a virtual machine. It may not be ready to be your primary operating system, but it's cool to see how far it's come in terms of speed and features. Check out our Windows 8 in-depth guides, from the Metro interface (which isn't great without touch, not that it matters) to the desktop, to Windows Explorer and the brand new Task Manager. While you're at it, you can check out some of Windows 8's lesser known features, too.

Once you've got everything up and running, be sure to check out our Lifehacker Pack for Windows and the Windows App Directory for a ton of cool programs.

Mac OS X

If you haven't used Macs since the 80s, now's a good time to take another look. If your desktop or laptop is compatible, you can turn your computer into a hackintosh. They're tough, but with a bit of troubleshooting, you should have no problem getting it up and running. You can also run OS X off a flash drive, or run it in VirtualBox on Windows. The latest version of OS X has some pretty cool features both secret and obvious., especially once you've de-iOSified it (though you can get a lot of those features in Snow Leopard, if you aren't a Lion fan).

Once you've got everything up and running, be sure to check out our Lifehacker Pack for Mac and the Mac App Directory for a ton of cool apps.

Linux

Working with Linux is a hefty undertaking, but we've tried to make it easy with our Night School course on getting started with Linux. Of course, if you have used Linux before, you could always try a new distribution, like the super-customizable Arch Linux (my personal favorite) to the netbook-friendly Lubuntu or Archbang. Even if you've done your fair share of distro-hopping, you might try a new desktop environment instead, or even something a bit more out of the box like Chrome OS. Programs like Lili make it easy, by creating versatile, go-anywhere bootable thumb drives so you don't even need to install anything on your system.

Once you've got everything up and running, be sure to check out our Lifehacker Pack for Linux and the Mac App Directory for a ton of cool programs. Check out our guide to getting cool desktop effects in Linux, too, while you're at it.

Putting It All Together: Dual and Triple Booting

If you like what you see and want to give your new OS a more permanent spot on your hard drive—without losing your old one—you can dual boot your computer. We've done guides on how to dual or triple boot your computer with Windows, Mac OS X, and Linux, whether you're on a Mac or a hackintosh-compatible PC. You can also dual-boot Windows 7 and Windows 8 side by side, or run all your OSes at once using VirtualBox. Once you've got it all set up, make sure you're able to share your data across all your operating systems, too, for super-seamless switching.

We're platform agnostic at Lifehacker, which is why we love dual- and triple-booting our computers. Unfortunately sharing data between operating systems can be a huge headache. Here's how to stay organized by keeping it all in one place.

There's nothing more annoying than booting into OS X only to realize you need access to some files on your un-readable Linux partition; or Windows; or any combination thereof. The more operating systems we put on one computer, the more our data can get scattered around different partitions that we can't read or write from other OSes. With the right drivers and a bit of organization, though, you can keep all your data in one central location, and read and write that data from any OS under the sun.

Of course, not everyone triple-boots their system, so I've divided this guide into easily scannable sections, so you can skip right to the sections that apply to your machine (i.e., if you don't have OS X, you won't need to know how to read HFS volumes, nor will you need any drivers for OS X).

Part One: Sharing Drives Between Operating Systems

One of the biggest roadblocks to making your data available through each OS are all the different filesystems each one uses. OS X uses HFS+ and can't write to NTFS drives; Windows uses NTFS and ignores pretty much everything else, and Linux has support for nearly everything (albeit with some serious hassle caused by stingy UNIX permissions). Thus, before you do anything else, you'll need to install the correct drivers in each OS for reading and writing to other filesystems. Here are the best choices we've found in each situation.

Note: while it's very likely that your OS X partition is HFS+ and your Windows partition is NTFS, your Linux partition could be any number of filesystems. Unfortunately, Ext4 (which is becoming the new standard) still isn't supported in most third-party Ext drivers. For the most part, the drivers in this guide will work with Ext3 and Ext2 formatted Linux drives only. If your drive is Ext4, you may have to clone your Linux partition, using an Ext3-formatted drive as the destination.

Accessing Mac and Linux Drives in Windows

Reading and writing to Linux drives is easy in Windows, but there aren't any free, read/write drivers for Windows, so you'll have to compromise somewhere. Here are your options.

For Mac Volumes

To install the Boot Camp drivers, just insert the Snow Leopard install disc into your Mac and install the drivers when prompted. If you're on a Hackintosh, you won't get this option, since the disc won't recognize your computer as a Mac. To install the HFS drivers on a Hackintosh, you can use this installer instead.

Unfortunately, these drives are read-only. If you absolutely have to write to your HFS partition, the only way to do so is to spring for either Paragon's $40 HFS+ for Windows 8 or Mediafour's $50 MacDrive 8. It isn't cheap, but sadly it's the only read/write option currently available.

For Linux Volumes

Luckily, there is a relatively pain-free Ext2/Ext3 driver for Windows called Ext2Fsd. Just download it and install it like a normal Windows program. When you get to the "Select Additional Tasks" stage, check all the necessary boxes for your setup (I chose to check all three). Once you're done, however, you'll get this error message:

To fix it, navigate to Ext2Fsd's install location (C:\Program Files\Ext2Fsd by default), right click on Ext2Mgr.exe, hit Properties, and check the "Run as Administrator" box under Compatibility. Then, double click on it to set up your drive. Double click on your Ext3 drive, click the Mount Points button, hit Add, and select a drive letter for your drive. I chose to create a permanent mount point for the drive so it's always mounted. You can choose whatever you want at this stage. Once you're done, you should be able to browse your Linux drive from Windows Explorer just as you would any other drive.

Accessing Windows and Linux Drives in Mac OS X

With the free, open-source utility MacFuse, you can enable support for Windows and Linux drives very easily in OS X. All it takes is a few simple installer packages. Before you install the drivers themselves, you'll need to install MacFuse. Then, install either (or both) of the drivers below depending on your needs.

For Windows Volumes

While Mac OS X can read NTFS partitions out of the box, you can't actually write to them. If you need both read and write support, you can install the NTFS-3G driver after installing MacFuse. Just head over to their homepage, download the software, and double-click on the package to install. When prompted, I chose to use UBLIO caching during the installation process, since my NTFS partition is on an internal drive and is unlikely to be unintentionally disconnected. When you reboot, you should have full write support.

Note that their homepage is a bit confusing—the people who work on NTFS-3G also develop a driver called Tuxera NTFS for Mac, which is not what you want (unless you feel like paying $30 for slightly better performance, in which case go for it). Make sure you're downloading "NTFS-3G for Mac OS X" before you install. You may have to scroll down the blog to find a post containing the latest download. It isn't the most well-organized homepage.

For Linux Volumes

To get Ext3 and Ext2 support in OS X, just download the Fuse-ext2 driver from this Sourceforge page and install the package. When you reboot, you should have read access to your Linux drive.

While the drive does support reading and writing, it's set as read-only by default. You can enable it by tweaking a configuration file, but I will note that while many have had success with this method in Snow Leopard, it keeps throwing me an error when I try to write to the drive, so your mileage may vary. To make OS X mount the drive as read/write, just navigate to /System/Library/Filesystems/. Right-click on the fuse-ext2.fs file and hit "Show Package Contents." Then, drag fuse-ext2.util to the desktop, right-click on it, and hit "Open With", choosing TextEdit when prompted.

Use Cmd+F to find the line that says OPTIONS="auto_xattr,defer_permissions" near the middle of the file. Add ,rw+ to that line inside the quotes, so it reads:

 OPTIONS=auto_xattr,defer_permissions,rw+" 

When you reboot, the drive should be mounted as read/write. Note once again that write support is a bit buggy in this driver, so just be wary.

Accessing Windows and Mac Drives in Linux

Most Linux distros come with full NTFS support built-in, as well as read support for HFS+. So, you only need to do anything extra in Linux if you want to write to Mac-formatted drives.

For Mac Volumes

By default, Mac OS X formats volumes in journaled HFS+ volumes. Journaling is a feature that improves data reliability, and unfortunately it makes HFS drives read-only in Linux. To disable journaling, just boot into OS X and fire up Disk Utility. Click on your HFS partition, hold the Option key, and click File in the menu bar. A new option to Disable Journaling will come up in the menu. Click that, and reboot into Linux. You should have read and write access to your HFS partition—however, the permissions on your Mac user's home folder will prevent you from reading or writing those files. See Part Two below to fix that problem.

Part Two: Putting All Your Data in One Place

This part is optional, but I've found that using one home folder to store all my data (and linking to that home folder in the other two OSes) makes life a lot easier, especially since a few of the drivers listed above aren't quite perfect. Plus, by putting all my data in one place, I can keep my music libraries synced together, pause torrent downloading in one OS and resume it in another, and so on.

First, pick which OS' home folder you want to use for this—I like to use OS X's home folder—and follow the instructions below to use it across OSes. Depending on your needs, you may choose to store all your data in your Windows or Linux home folder. The best way to decide which to use is by which OSes you use the most—since I barely use Windows (and thus didn't feel like paying $40 for a read/write driver), I used my OS X partition as my main data dump, since it's easy for Linux to read and write to it. The main idea is to not use a partition that has bad write support in an OS you use often—so, if you're a heavy OS X user, you wouldn't want to put all your data on your Linux partition, since the OS X driver isn't so great. Similarly, if you use Windows often, you wouldn't want to put it all on your OS X partition (unless you want to pay $40 for MacDrive). Think about which partition would be most convenient for you and go with it—after all, you can always move your data later if you so choose.

Making Mac and Linux Home Folders Play Nicely with One Another

The great thing about OS X and Linux is that they are both UNIX-based operating systems, so they work pretty well together if you can get everything set up correctly. When you create a user in either operating system, it gives you a User ID number. OS X starts these numbers in the 500s, while Linux usually starts in the thousands. This is problematic because a different "user" owns your home folder in OS X than owns your home folder in Linux. As such, Linux will deny you access to your OS X home folder, since you don't have the right permissions to access it.

There's an easy fix, however—we just need to change our UID in one OS so that it matches the UID in the other. Unless you have a reason for choosing otherwise, we're going to change our Linux UID to match our OS X one, since it's a bit easier. By default, the first user in OS X has a UID of 501, but you can double check this by going into System Preferences in OS X, right-clicking on your user, and hitting Advanced Options. If your User ID is something different from 501, replace 501 with your other UID in the terminal commands below.

Boot into Linux (we're using Ubuntu in this example) and fire up the Terminal. First, we're going to add a temporary user, since we don't want to edit a user that we're currently logged into. So, run the following commands in the Terminal, hitting Enter after each one:

 sudo useradd -d /home/tempuser -m -s /bin/bash -G admin tempuser  sudo passwd tempuser 

Type in a new password for the temporary user when prompted. Reboot and log in as tempuser. Then, open up the Terminal and type in the following commands, once again hitting enter after each one (and replacing yourusername with your Linux user's username):

 sudo usermod --uid 501 yourusername  sudo chown -R 501:yourusername /home/yourusername 

This will change your Linux user's UID to 501 and fix your home folder permissions so that you still own them. Now, you should be able to read and write to both your Mac and Linux user's home folder, no matter what OS you're logged into.

You may also want to fix your login screen, since by default Ubuntu won't list users with a UID of less than 1000. To do this, just open a Terminal and run gksudo gedit /etc/login.defs and search for UID_MIN in the text file. Change that value from 1000 to 501, and when you reboot your user will be listed in the login screen.

Lastly, log back in as your normal user and run sudo userdel -r tempuser to delete the temporary user we created earlier.

If you like, you can create symlinks in one of your home folders that point to your main home folder for quick access. For example, since I use my OS X home folder as my main data dump, my Linux home folder is mostly empty. So, I created symlinks in my Linux home folder for Documents, Videos, Pictures, etc. that point to the equivalent folders on my Mac partition. You can do this by using the following Terminal command:

 ln -s /path/to/linked/folder /path/to/symlink/ 

If you're using your Linux home folder as the main one, you can use this same command to create symlinks that link to your Linux home folder instead.

Note that if you're using your Mac partition as the main home folder, you'll probably also want to automatically mount it in Linux when you start up. You can do this by adding a line to the end of /etc/fstab. This will vary from person to person, but mine looks like this:

 /dev/sda3 /media/Data auto rw,user,auto 0 0 

Where /dev/sda3 is the location of the partition containing the home folder and media/Data is the path I want to use to navigate to it.

Using Libraries in Windows 7

Since Windows doesn't support UNIX permissions, you won't need to mess with them at all—you should be able to read and write to your Mac and Linux home folders without a problem (as long as you have the correct drivers installed). To make them easier to access, we can use Windows 7's awesome Libraries feature, which allows your Documents, Videos, Pictures, and other "libraries" to link to multiple folders on your drive, so you can access the files stored in your main home folder from shortcuts in the Windows Explorer sidebar (and in many applications).

To add those folders to each library, open up Windows Explorer. Right click on a Library (say, Documents), and hit Properties. Hit the "Include a folder" button and navigate to the Documents folder in your main home folder. Hit Include, and you should see it show up in the list. You can even click on it and hit "Set Save Location" to set it as the default save location for the types of files Windows associates with that Library. Repeat this for your other libraries and you're all set on the Windows front.

Now, I just make sure all my applications point to the same directories in each OS. For example, I have Amarok watching my iTunes folder for new files, so when I add music to my iTunes library, it will show up automatically in Amarok (similarly, I can add newly downloaded music to iTunes' "Add Automatically to iTunes" folder for it to automatically show up in both Amarok and iTunes). I tell my torrent downloader in each OS to download new torrents to the same location, so if I want to leave Linux and continue downloading a torrent in OS X, I can just reboot, add the torrent to Transmission's queue, and it will pick up right where I left off in Linux. This way, you don't need to use space-limited solutions like Dropbox (as awesome as they are for inter-computer syncing) to sync your data—it's just always there. There are, of course, other ways to do this, but this is the way I have it set up. How do you share your data between multiple operating systems? Share your favorite strategies in the comments.

We've walked through how to triple-boot your Mac with Windows and Linux, but if you're using a shiny new Hackintosh, the process is a bit more complicated. Here's how to get all three operating systems up and running on your new PC.

While the Chameleon bootloader (the default boot screen for your Hackintosh) is a great friend to Hackintosh builders, Windows and Linux try to muck everything up by attempting to take over your computer with their own bootloaders, resetting the active partition, and throwing your partition tables out of sync. There are two ways to triple boot your Hackintosh. The first is very straightforward and allows you a lot of flexibility, while the second is much more complicated but offers other advantages depending on how many hard drives you have. This guide assumes you've already installed Mac OS X as described in our most recent Hackintosh guide, and, if you're using the second method, that you still have the iBoot disc handy. You'll also obviously need the Windows 7 and Linux installation discs as well. If you've got everything ready, follow the instructions below to get Windows 7 and Linux living harmoniously on the same PC.

The Easy Method: Use Multiple Hard Drives

By far the easiest way to triple boot your Hackintosh is to install your other operating systems to separate hard drives. Chameleon can see operating systems on any hard drive in your computer, and one of the advantages of building a desktop is that you have tons of extra drive bays to fill up. Chances are you probably have some extra drives lying around anyways, so this wouldn't be too out of the way. This method doesn't even warrant a how-to—you just install your extra drives in your system, then install Windows and Linux on each one using the default settings. You can even stick them on the same drive, if you want—it's only when all three get together that you start to have problems. Photo by Justin Ruckman.

If, for some reason, you want to keep them all on the same drive, roll up your sleeves and read on.

The Complicated Method: One Drive to Boot Them All

Putting all three OSes on one drive isn't difficult, but you do need to perform all the steps correctly and in the right order, or you'll be left with a confused mess on your machine. The only big advantage of this method is if you don't have any extra hard drives lying around, or if you have a large enough SSD and want to take advantage of its speed in all three OSes.

Step One: Partition Your Drive

Right now, you should have a drive with just one partition containing Snow Leopard (plus your 200MB EFI partition, which won't be visible in Disk Utility). Start up Disk Utility and click on the drive containing OS X in the left sidebar. Head over to the Partition tab, and click on your Mac OS X partition. Hit the plus sign at the bottom of the window twice, so you have a total of three partitions. Head to the upper right-hand corner of the window and name the second partition WINDOWS and the third one LINUX, formatting them both as FAT32 for now. If you need swap space for Linux, you can add a fourth partition, but nowadays this seems pretty unnecessary, so three partitions should be just fine. Hit the Apply button and let it work its magic.

When you're done, insert your Windows 7 installation disc and restart your computer.

Step Two: Install Windows 7

Boot from the Windows 7 disc and head into the Windows installation. Make sure you do a Custom install, and when you're given a list of hard drives, click on the partition named WINDOWS and hit "Drive Options (Advanced)". Click Format to format the drive as NTFS, and then hit Next to start the installation. Your computer will reboot a few times, but you won't have to mess with it at all, so go away and come back when it prompts you to name your computer.

As always, Windows is the biggest problem child in this debacle. When you reboot, you won't be able to boot into OS X, but that's fine—we'll deal with all that in a moment. First, we're going to get this Linux installation out of the way.

Step Three: Install Linux

For the purposes of this guide, we're going to install Ubuntu 10.04, but you can use another version of Ubuntu if you want, or another distro altogether (like the super awesome Arch Linux). Just make sure you install Linux to the correct partition and make extra sure that you install Grub to the same partition to which you installed Linux, as described below.

Boot up from your Ubuntu CD and head into the installation. The first few steps are pretty self-explanatory, it's when you get to the partition window that you want to pay attention. Hit "Specify Partitions Manually" and click Next. Double click your Linux partition's entry in the table (at this point, it should be the only FAT32 formatted partition on your drive). Under "Use As", choose your desired filesystem (If you aren't sure, use Ext4, which seems to be the new standard). Check the "Format the Partition" box and choose / as the Mount Point. Hit OK. Before moving on, note the name of your Linux partition—the name will be something like /dev/sda4—and hit the Forward button to continue.

In the last window, where it says "Ready to Install", hit the Advanced button. Under "Device for boot loader installation", it should say something like /dev/sda. Change this to /dev/sda4, or whatever the name of your Linux partition is. Ordinarily, Grub will install itself to the Master Boot Record of the drive, because it wants to be your primary bootloader. In this case, we're already using Chameleon, so we're just going to stick this on Linux's partition, since we won't be using it to get into Windows or OS X. When you're ready, hit the Install button and let Ubuntu do its thing. When you're done, restart your computer.

Step Four: Fix the Windows Bootloader You Just Broke

You'd think keeping Grub away from Windows would leave Windows' bootloader untouched, but these operating systems just don't like to play nicely together. Unfortunately, when you first installed Mac OS X, you set your hard drive to use a GUID partition table (GPT), which is not fully compatible with Windows (Windows and Grub really prefer an MBR partition table). Now that you've installed Mac OS X, Windows, and Linux side-by-side, your drive is a GPT/MBR hybrid, and your partition tables are "out of sync". To make the GPT and MBR tables play nicely with one another on the same drive, you need to sync them with a program called gptsync in Linux.

So, grab your iBoot CD and use it to boot into your new Linux partition (since Chameleon is strangely missing—we'll get to that in a second). Download gptsync from your distro's repositories (though Ubuntu users may want to use the .deb files available here instead of the older versions still in the repositories). Once it's installed, pull up a Terminal window and type:

 gptsync /dev/sda 

where /dev/sda is the drive containing all your partitions. If you aren't sure which one is the one you're using, type in fdisk -l to see a list. Note that you aren't using it on just one of the partitions (e.g. /dev/sda1), you're using it on the entire drive. Once you're done, your computer should successfully boot into Windows whenever you reboot.

Step Five: Set The OS X Partition as Active

When Windows installs, it makes itself the active partition on your computer, which means when you restart, your computer will just boot you into Windows as if OS X and Linux weren't even there. We want the active partition to be our OS X partition, since it contains Chameleon, which lets us choose between the OSes when we start off. To pry Windows' greedy hands off your hard drive, just open up the start menu, right-click on Computer, and hit the Manage button.

From there, click on Disk Management in the left-hand sidebar, and find your OS X partition. Right-click on your OS X partition in the map and hit "Mark Partition as Active". Then, reboot your computer.

If everything goes well, you should be greeted once again by the familiar Chameleon bootloader, which will now list Mac OS X, Windows, and Linux as available boot options. Double check and make sure each of them boots correctly. If they do, you're finished! Enjoy your new triple-booting PC. If not, you may have done something wrong in the above steps. You can try googling any error codes you get and fixing it that way, or re-syncing the partition tables and trying again, but because of the complications in Windows and the GUID partition table, it might be simplest to just start from scratch. Back up your data in your OS X partition, reformat the entire drive, and start over. It's a pain, but like we said before—these three OSes really, really don't like to get along with one another when you try to put them all on the same drive.

If the pain of starting from scratch is too much to bear, reconsider the multiple-drive option—it won't give you the speed boosts of an SSD (unless you buy three), and it might cost a bit more if you don't already have drives lying around, but on the occasion that you need to reinstall one of the OSes or reformat part of your drive, it will be completely hassle-free, unlike the above method which has me pulling my hair out after just one day.

Lastly, as always, these may not be the only ways to triple boot your Hackintosh, but it's the method that, after a few tries, I've found works pretty well. So, if you have your own preferred method (or tips for others trying this one), share them with us in the comments.

Apple has streamlined the process of dual booting Windows on your Mac, but when it comes to Linux, Boot Camp isn't so friendly. Here's how to triple-boot your Mac with OS X, Windows 7, and the shiny new Ubuntu 10.04.

If you're a Mac user, you may have already used Apple's Boot Camp to get Windows on your system for those must-have programs. With a fast new Ubuntu out, however, you might want to give it a try—but installing Linux isn't exactly easy on Macs, since they don't recognize it by default.

Also complicating things? Linux and Windows' boot loaders will attempt to take over one another. Usually, this is a good thing, because Linux's multi-system loader makes the experience more seamless for PC users—but on a Mac, this really just makes things more difficult (no one wants to go through two menus to choose their OS). As such, installing Linux needs to be done with certain settings applied, or you'll be left with a jumbled mess. Here's a step-by-step guide to making your triple booting experience as user-friendly as possible.

Note that I will go through the steps to installing both Windows 7 and Ubuntu 10.04, but if you already have Windows installed, that shouldn't be an issue—just skip the Windows installation step and move on to installing Ubuntu, which is the more complicated (and important) part anyways.

Install the rEFIt Boot Menu for Macs

Before we do anything else, we're going to install a new boot menu for your Mac that will make your life during and after installation much easier. rEFIt will show up every time you start up your computer, asking you which OS you want to use. By default, it will boot into OS X after 20 seconds of inactivity (so you don't have to be there every time to choose). It's super customizable, though, so you can change your default OS if you want to, as well as tweak other settings to fit into your workflow as best as possible.

Head on over to rEFIt's SourceForge page and download the DMG for the most recent version of the installer (0.14 at the time of this writing). Open it up and launch the installer package, and go through the installation process (which is pretty self-explanatory; it'll do all the work for you). Afterwards, restart your computer to see if it works! If everything goes as planned, your screen should look something like the screen at the top of this article (though if not, you might have to restart twice to get it to show up). Obviously, it'll only have one or two icons instead of three—the others come next!

At this point, the rEFIt boot menu is fully functional, though if you want to customize it, you'll have to edit your configuration file. More information on this is available in rEFIt's documentation; I won't get deep into it now, but it's not very difficult to tweak things like the default OS, or which tools show up along the bottom. You just need to "uncomment" the given option by removing the # before the relevant command in the text file. You can also customize the icons by swapping your own .icns with the default ones in rEFIt's folder on your hard drive. You can do that now, or move on to partitioning your disk.

Partition Your Hard Drive with Disk Utility

We won't be using Boot Camp to partition our disk, mostly because we don't need to. Since we're triple-booting, it's easier to see it all at once, rather than let some tool do it for us (if you've already installed Windows using Boot Camp, though, that's fine—just ignore the Windows parts of this step). Open up Disk Utility, click on your main drive (the very top option in the sidebar) and head to the "Partition" tab.

We're going to make three new partitions; one for Windows, one for Linux, and one for our Linux swap space, the space Linux uses if it runs out of memory. To do this, just click on your Macintosh HD partition. If you have multiple partitions already, click on the one from which you want to take back some space. Next, hit the plus sign enough times so that you have four total partitions. Click on your first new partition (the one under "Macintosh HD") and on the right side of the window, type "WINDOWS" in the name box. Format this Windows partition to MS-DOS, then make the size whatever you want.

The sizes don't particularly matter, as long as your OS will fit on the partition, and you have enough extra space for whatever you want. I partitioned 50 GB to each OS—probably overkill, but hey, I've got a big drive. Do the same for a Linux and Linux swap partition, formatting each to MS-DOS (the format isn't super necessary, but at least for the Windows installation it does make the process easier). Hit the apply button and let Disk Utility do its thing—it'll seem like it stops responding, but just leave it be for a minute, and you should be all set. Once it's done, move on to the next step.

Installing Windows 7

Insert your Windows 7 install disc and restart your computer, unless you've already installed it, in which case, move on to installing Ubuntu). As your computer starts up, listen for the familiar Mac startup sound, then immediately press and hold the Option (or "Alt") key on your keyboard, until you see a drive icon with the word rEFIt under it. You'll need to give your system a second to check the CD drives (assuming you're running Snow Leopard, which is a little slow at doing so), but your Windows CD should pop up on the right. Click on the CD icon, then hit Enter to boot into the installation. You might also get a screen that says "Press any key to boot from CD. . .", in which case you'll have to do what it says, or else just restart your computer.

Go ahead and navigate through the first few steps of the installation. When you're asked what type of install you want to perform, choose "custom install", so you can pick and format the partition. You'll want to choose the one named WINDOWS (obviously), though you'll have to format it by clicking "drive options" and then "Format". It should reformat that partition to NTFS for you, after which you can hit the next button. It'll take a little while to install, and it'll restart a few times during that process—whenever it does, select the Windows partition on boot (which should show up in rEFIt now, so you won't need to hold option down again).

When it's done and you finally get to the Windows desktop, you can go ahead and install the Boot Camp drivers from your Leopard or Snow Leopard install DVD. Since your eject key won't work yet, you'll have to eject your Windows disc manually by going into Windows Explorer, clicking on your optical drive, then choosing the "Eject" button in the toolbar. After inserting your Snow Leopard DVD, it should start automatically with the option to run setup.exe. Pick that, then let the installation run. Once you're done, head back over to OS X, so you can burn and install Ubuntu.

Installing Ubuntu 10.04

If you don't already have an Ubuntu installation CD, you'll need to head back into your Mac system (or Windows, if you want to give it a go) and grab the ISO from Ubuntu's website. Make sure you get the right one for your machine, whether it be a desktop/laptop or a netbook, and 32- or 64-bit. Once it's downloaded, burn it with your burning program of choice (I'm quite partial to the flexible, open-source Burn myself, though you could also do it with Disk Utility). Once it's burned, keep it in the drive and restart your computer, once again holding option at the startup sound and clicking on the CD that shows up in your boot menu. It will say it's a Windows disc, but don't worry—it's the right one. OS X is just a little confused when it comes to the world outside itself.

It'll take a few minutes for the CD to boot, but you should eventually be presented with the option to try Ubuntu or install it on your computer. Choose install, then go through the first few steps of the process, picking your language, time zone, and keyboard type (USA probably works fine, but I usually pick USA - Macintosh because, you know, that's what I have). When you're presented with the partition window, choose the bottom option to "specify partitions manually"—this is where the fancy footwork comes in.

Double click on your Linux partition's entry. If you've been following this how-to to the letter, it should be /dev/sda4. You'll be presented with a window in which you manually set the partition's characteristics. I chose to use the partition as Ext4, although you can pick something else if you want—Ext4 seems to be the new standard, so I'd recommend it if you don't know the difference between them all. Check the box to format the partition and make the mount point "/". Hit OK and double click on your 1 GB partition at the end of the drive, set it to be used as a swap area, and then hit OK. At this point, your window should look something like this:

Go through the rest of the installation until the last window, where it's ready to install and asks you to double-check everything. Hit the advanced button. Make sure "install boot loader" is checked, and change the device for boot loader installation to the same partition on which you installed Linux (in the above case, /dev/sda4). Hit next and let 'er rip. When it's done it should restart your computer and your rEFIt boot menu should contain an option for all three operating systems. If you can successfully boot into both partitions, congratulations! You've got a working triple-boot system.

Unfortunately, installing drivers in Ubuntu is not nearly as easy as installing them in Windows. Actually, it's probably the hardest part of this entire process. It's model-specific to each Mac, so I can't detail it all here, but the Ubuntu Community Documentation is usually quite good at compiling a how-to for each model, so head on over to the page for your model of iMac or MacBook to get everything up and running. Follow the instructions as closely as you can, don't be afraid to ask for help on the Ubuntu forums, and God be with you.

There are, of course, a few different ways to set this up (see our guide to dual booting Windows 7 and Ubuntu on a PC for a few possible modifications, such as creating a swap file within Ubuntu instead of on a separate partition), but in general this is a straightforward, user-friendly way to get it all working. You won't have to deal with a bunch of different boot menus, and you won't have to deal with OS X's limitations in recognizing Linux drives at boot (though you still won't be able to see your Linux partition from the Mac desktop). If you've got experience with this, though, we'd love to hear your preferred method of triple booting your Mac—tell us about it in the comments!