I am pretty sure you can, you just need a partition manager, WinXP has one, and Linux has several, like Grub. This will run at boot, and allow you to select what operating system ( or Linux build for that matter ) you wish to run. One of my PC's does this every time I boot it up. I get asked if I want to run either of 2 Linux builds, DOS, or Windows XP ( it calls this DOS also ) This all resides in the MBR, which tells the machine which boot sector to load, hence which OS to run. Grub takes over this process for example.