your current system are really good, man... What is your PSU? Monitor?
PSU is 700W antec and the screen is samsung p2250 . . . . 1900*1080, 2ms responce time and 50,000:1 contrast ratio.
do you have an answer???
Definitely the card although the HD5850 is a better buy
Upgrade the GPU, you already have a decent CPU.
like jyjjy said, if u want to upgrade, go for at least HD 5850, it will great... if u can afford 5870 then go for it..
You have an excellent PC Just upgrade you GPU to something not less than 5850 or 5870 Or You can wait some time to see NVIDIA new generation cards Either you can buy a NVIDIA card or you can buy a ATI card at fewer cost
Your platform is still fine, just upgrade the GPU for now.