New CPU or New Videocard?

the vid card would help more, but the cpu is the base upon which the pc is built, so they go hand in hand, get the 945 or the 5770, either one will increase the performance of ur rig, but you wont see full results until you get both.

For games, the graphics card should give the bigger boost. Though you should consider overclocking some more.

Even with a better cpu, the boost you'd get with a 3870 would be pretty marginal compared to another gpu.

5770. For sure. The CPU wont bottleneck a single GPU, probably a dual GPU yes but single nah.

Get a 5850 or a 5870 if you can splash the cash as Crysis will benefit more from a better GPU given your running a quad at 2.6 ... around 3Ghz seems to be the sweet spot though (where no more gains produce a better result given a mid to high end graphics card).

What mobo do you have there?

Can you get the dilithium crystals to resonate any higher?

9600 @ 2.6 ... is it a black?

The 5 series ATI cards are quite pricey at present ... but a fast single slot solution.

Do you just game? Any chance of getting both? Athlon II quads and Phenom II triples are in the low $100s right now, any chance of squeezing both in? If not, upgrade the CPU now and GPU when the 5XX0s pricedrop. No CPU pricedrops in sight right now, unfortunately.

You'll probably feel a nicer bump going with the newer GPU. I'd go with the 5770 first, then the CPU down the road.