We purchased a laptop that had Vista on it, but without a Vista install disk, just one of those recovery CD's. We wanted to have Vista on the laptop to experiment with but need to use the laptop in our corporate environment which requires XP. If XP is installed 2nd, it doesn't ask you if you want to set up a dual boot, so here is how to do that.
http://apcmag.com/5485/dualbooting_vista_and_xp