Seems strange that you say in the first post that since you re-installed nothing works, thats what makes me think it may be something to do with the graphics card driver.

When XP is installed it sometimes installs a default driver that looks ok but is not capable of running games, the easiest thing to do is make sure that your XP is fully updated, graphics card drivers are not usually set to update by default, as they are optional upgrades, you will need to tick the box for it to update it.

Failing that have a look to see what graphics card you have and update it from the manufact website.

You may have already done this, just tell me to shut up if im covering stuff youve already done