7900gtx vs 8800gts

I would like to know if I would get any good performance increase by upgrading my current XFX 7900 GTX Extreme Edition 512mb to the 8800 GTS 320mb. I can't see the point on getting 640mb version or even GTX, before games like BioShock or Crysis are out.
I get almost 12K in 3DMark 2005 with my current rig: C2D 6600, Asus P5B-E Plus, 2gb DDR2 667.
The main reason why I want upgrade now, is S.T.A.L.K.E.R.

u can almost maxed out S.T.A.L.K.E.R with that vga ( 7900gtx ) ... u dont need to upgrade just for 1 game but latter on u can just go for the 8800gtx when games like crysis & bishock comes out:)pepsiboy987

I know I can, almost but not. Maybe I need 2gb exstra ram or a Raptor harddrive. What do you think?

Inno3D are a cheap brand. Just don't expect a games bundle with the card. Cyborg-21

I am not expecting to get anything esle for that price.