Well obviously the first thing to check is to make sure you have your video card drivers are up to date. Check to see if your card is an AMD or NVIDIA card. Google the card drivers and download and install them.
The other thing is DirectX 9 - you can google this and download it from Microsoft.
One problem that I'm having right now is that (with the information given) you updated an old machine running XP to Windows Ultimate - you may have a faulty install or your machine can't handle the larger operating system.