|This is a little complicated, but:|
Get nLite - it is a program to recreate setup disks.
Find out what hardware drivers you need for XP to control your display and slipstream (with nLite) them into a new setup disk. Use this disk to install XP.
Note: Because Vista is newer than XP, you may need to wipe Vista from your hard drive first or you may need to create a seperate partition for XP to run on. If so, you can use EaseUS Partition Manager.
Hope this helps!