How can I triple boot Windows XP, Ubuntu 9.10 and Windows 7? Which OS should I install first?
If you need an additional resource, you can use the apcmag.com dual-boot guides and adjust accordingly.
Download and burn GParted Live (just do a google search) to a CD and boot your computer. Use GParted to create a new partition (at least 10-15 GB) for W7. Make sure it is associated with the XP partition so that the W7 boot loader will recognize XP. When you boot W7, it will give you the option to boot XP as the "Earlier Version of Windows."
Then, you either need to adjust the W7 boot loader with EasyBCD (instructions can be found on the apcmag guides) or, preferably, reinstall the GRUB Boot loader by doing the following:
Insert the Ubuntu Live CD (or flash disk or whatever) and select "Try without changes to computer." Once it loads up, open a terminal and type "sudo grub"
Then enter the following commands in order.
Reboot, and it will go directly back to Ubuntu. Now you'll need to edit GRUB to get the Windows partitions. You have two options - enter BOTH Windows partitions into GRUB, or just enter W7, and use the W7 bootloader to then select XP. To edit grub, key into the terminal "sudo gedit /boot/grub/menu.lst" (or replace gedit with whatever program you prefer) and make sure that the option "hiddenmenu" has a '#' in front of it to make it visible. Then go to the very bottom where all the Ubuntu kernels are listed and add the following (NOTE: The location (hdX,X) may be different for your install):
Not directly an answer to your question but as I used to dual boot different operatin system and now use virtual machines I thought I'd offer it as a suggestion. As I'm a .Net developer I have 7 installed as my host operating system simply as this is what I use most often, I then use VMware and run a copy of Ubuntu as a virtual machines. I do the same with XP but I'm using it less and less these days. Performance of the Virtual machines has been fine for me I even run a Windows Server 2008 to test my applications. If you have the hardware I'd try this out as it might work for you as well.
Have you looked into XP Mode in Windows 7, this might be of use to you if you need Windows XP.
I used VMware in my discussion simpley as that's what I use however VirtualBox is an open source alternative that will allow you to do the same.