Can I ask which graphics card it is?
You need the drivers for the hardware for it to run, have you double checked the graphics card is the one you've plugged into your monitor? A lot of the time people will install a graphics card and plug their monitor into the on board slot.
If all of this doesn't work, it may just be they're not compatible, a lot of the time certain hardware won't work with XP because it's not supported by anything anymore.