How to triple boot Linux ubuntu, Windows 7 and Windows XP
Starting with a cleanly formatted harddisk,
1) using the ubuntu start up CD, boot into ubuntu
2) partition hard drive for different OSs: small (4 GB) for XP, large (20 GB) for Win7 and as needed for ubuntu
3) first install ubuntu on its partition
4) second install Windows 7 on its partition
5) lastly install Windows XP on its partition
6) At this stage, when you restart your computer, it will automatically boot into XP with no menu option for which OS to boot into
7) boot from ubuntu CD (bypassing hard drive) and once in ubuntu, set g (ubuntu boot) as primary
8) reconfigure gstart menu for what you want your primary OS to be and set the time out for selection
9) voila, a triple booting windows and linux machine.
I set this up on my Gateway ec1803u semi-netbook for my 2 year motorcycle trip around the world and it's been working great. Haven't needed XP much but it's there in case 7 crashes. Still learning about ubuntu.