It will vary slightly from bios to bios. In HP it's called SATA Native Support and needs to be disabled, Dell simply has a hard drive interface option to change to SATA. I'm unfamiliar with your specifics, but it should be fairly easy to recognize the setting you need to change.
A quick google search found me a thread that seems to point to Sager bios having a simple setting change from ACHI to IDE to install XP.
I will try it out. Thanks for the help everyone who posted. Vista is pretty, but...gd its giving me a headache