i wish i had this budget! having said that i think u should go for;
amd 64 3700+(1mb cache, 2000mhz)
asus compatible mobo depending on which processor u choose! got to support the amount of fsb provided by the processor
120gb sata(min 7200 rpm)
2x512(min 400 mhz) corsair or kingston
audigy 2(zs or value depending on whats left of ur budget)
min 450watt genuine output psu
ive not been fixed on 600pd ....(+- 50)...once u go for a sys purchase, we all understand theres something extra that we can pool in!
listen........ull have to strike a balance between ur processor and graphic card........u can go for the 6800 ultra, but then ull have to go for amd 64 3200+(512k cache, 1600mhz)....spend a 100-150 more and u can have the 3700+ and the 680 ultra. whatever u do im sure its gonna be a kick... sys. happy shopping.