Check and see what Grpahics Adpater it takes, Some then Used PCI-E, But I would bet more along the lines of agp if it was a value version. Then again if your only gonna be playing CS:S you wont need much as far as upgrades go. Go look at all the parts and post up the specs so people can give you more informative suggestions. Even with a cheap version 8600 CS:S would play extremely well if the other components are up to par.