http://gparted.sourceforge.net/livecd.phpgparted live cd
or if you are going to install linux anyway, it usually comes with either gparted or cfdisk or both. so
1. insert linux/gparted disk
2. run the partition application
3. reboot
4. install xp
5. install vista
6. install linux (to get the boot manager automatically set up all OSes)