Hey everyone! Just to let everyone know that I am successfully triplebooting Mac OS X Leopard, Windows XP Home, and Linux Mint Gloria!

I thought I would post a howto, because I had a hard time finding one. Basically the main thing I did to get it to work was to get rid of the GPT/MBR hybrid on the hard disk, and switch to MBR only. (This might work with GPT only if you're running Windows Vista 64 and a linux distro that supports GPT (elilo or grub 2?), but I have not tested this option). I was worried that doing this would cause Mac OS not to boot, but apparently rEFIt can boot Leopard without a GPT. (I have not tested this with Tiger or Panther and/or without rEFIt, so doing that is at your own risk )

What you need:

1. rEFIt, found at http://refit.sourceforge.net/. It is an open source boot loader for the mac. It understands both GPT and MBR, and can boot from both.
2. iPartition, found at http://www.coriolis-systems.com/iPartition.php. This is not open source, and at $45, it is a little pricey. However, it is the only program I've found that truly "understands" a dual GPT/MBR hard drive scheme, and it is quite flexible. If anybody knows of an equivalent open source program, please let me know! (cfdisk/fdisk is MBR only, and Parted/Gparted does not understand the hybrid system, and cannot modify both schemes)
3. Your favorite Linux distro. I used Linux Mint Gloria, but any distro should work. I have not tested this with lilo, but it should be fine with Grub 1 or 2.

Instructions: (You will want to back up your data)

1. Install rEFIt.
2. Install iPartition and create a bootable CD using the included utility.
3. Boot from the iPartition CD and select "iPartition" (this may take a while)
4. Select the target hard disk.
5. In the inspector window, change the partition scheme from "GUID Partition Table" to "Master Boot Record".
6. Resize the Mac OS (HFS) partition to whatever size you want.
7. Create or move the Windows (FAT32 or NTFS) partition. I installed a fresh copy of Windows for this test, but if you have a current copy of windows (from boot camp) you should be able to use it.
8. Install Windows from the install disk and format the partition, if needed. (This *will* take a while ). Verify that Windows works as well as it can (It should show up in rEFIt).
9. Install your favorite Linux distro. You will have to create and format the third partition from here, because iPartition doesn't understand most linux filesystems. If you have the option, install grub in the root partition. If you install it into the MBR, the rEFIt menu will not work correctly. (The "Linux" and "Windows" options with both show the GRUB menu. Windows will still boot from here if a chainloader option is on the menu, but it's an extra step to take.)
10. You should be done!

Note: after deleting the GPT, the rEFIt menu will take a long time to load for the first few times. Don't panic - after a few startups, it was snappy again

Feel free to comment/modify/ask questions (Although I may not be able to answer them)

Probably helpful to someone out there, congratulations.

Next month Snow Leopard is out.
I intend to upgrade than I can start it all over again.
Beside that it seems to be quit easy to install APT-GET in Leopard , so a wide range of linux applications is open to you.
Up until now I keep my Linux BOX apart from my MAC PRO workstation .
Not totally as they are on the same modem-router often login in my MAC box from the linux box

That's probably the ideal thing to do. However, I only have one computer right now, so getting all three OSes on it was a fun challenge. I actually started to try to do it with Linux from Scratch, but eventually gave up because it was too time consuming to learn and install it all .