• Supports 64-bit AMD® Athlon™ 64FX/64 processor (Socket 939)
• Supports 3000+, 3200+, 3500+, 3800+, 4000+, FX53 and FX55
those would be the cpu options. As for the vid card a 8800GTS would be great if you can afford it. If you don't need dx10 or don't want to spend that much money then you could get something like a ati x1950 pro.
Also if you choose to go with the 8800GTS then that most likely means you will need a new psu too.
How much can you spend? (total for all the parts)