reinstall DirectX 9
first the AGP drivers, chipset drivers, all the windows XP updates ideally first.
When you say you had to re-install XP Pro I take it you have a dedicated Microsoft CD and not a Factory restore format ?.
Did you install the XP Pro in FAT 32 or NTFS ? If you HDD is bigger than 34GB (before windows) then NTFS file system should be used.