The fastest PCI video card for gaming is the Xtasy Radeon 9100 (dont be confused by the 9*** names, higher isnt always better) Only problem is, its very hard to find it as they stopped making them. Good luck tho!
Edit: Oh, and if you are going to get the 9250, MAKE SURE you see the words "128-BIT" on it. DO NOT get if it is 64-bit. Its a horribly crippled version.