Bang for my buck?

Okay, so I need help choosing my next upgrades for my PC. I%26#39;m currently contemplating:  Intel Core 2 Duo Cornroe 2.13Ghz +Gigabyte GA-965P-DS3 Intel P965 + 2GB Corsair DDR2 SDRAM------------------------------------about $480 OR ASUS EN8800 GTS 640M ------------------------------------about $ 400  I need to know which one of these two upgrade choices will give me the largest fps boost in current and upcoming games. At first I thought the videocard might give me much more speed, but since my CPU is slightly more outdated than my videocard, and since many newer games seem to be trying to use more CPU horsepower, I%26#39;m kind of confused as to which will help me out more in the long run. My current specs are: AMD 3800 X2Nvidia Geforce 7800GTX1 GB generic DDR RamASUS A8N-SLI 600W Power Supply  Thanks! Bang for my buck?
Thast tough, you would see more of an increase in fps with the gpu (im pretty sure) but if you upgraded the cpu, RAM, and motherboard, you could wait (ati is releasing thier dx10 cards soon)Bang for my buck?

I say overclock your 3800 X2(they overclock good) it wont be as good but not that far from c2d, and get the 8800.You should be able to get around 2.7Ghz on air, That%26#39;s not bad, upgrading to c2d will be better but I dont think good enough to make it worth the money.  
Forgot to mention in my post, I%26#39;m in the same situation as you, though I have a pentium d 2.66 ghz and only an x200 right now :\ I want to upgrade to an 8800 gts 320 mb, but I%26#39;d be bottlenecked. So I%26#39;m going to buy a new psu and an 8800 gts, then around fall/christmas, a new motherboard, cpu and some more ram.