Originally Posted by SiGn
you will need your mobo (motherboard) drivers installed.
Precisely, XP isn't the all knowing os that Win7 is, you'll need to load drivers for chipset, lan, audio (maybe) etc.
Go into Device Manager and note which devices need drivers (they should have a yellow exclamation mark by them) then head to the board manufacturers site and see if they have the driver available.
XP x64 wasn't very well supported so good luck.