Smilers way will work in xp too.rather than use the drivers on the disc though which will be out of date,download the latest one from click here
uninstall the ati control panel first via add remove programs(do not restart)
uninstall the driver next via add remove and restart the computer.
click cancel twice when prompted to install the drivers.click the downloaded one and follow instructions. if you are using the ones on the disc then dont click cancel and point it to your cdrom.