Definetly go with the 8800. Try to get the GTX even the superclocked version. I don't see a 7950 beating that. And it is DX10. IMO it's a waste of money to buy the 7950 with DX10 on it's way.
7950gt is comparable to the 8800gts 320mb <- if your not planning on running insane resolutions this is a great card to look into. will not cost you much more than the 7950 and i will actually probably perform better. I bought my 7950 and I'm wishing I had an 8 series card now after seeing all my buddies getting them and how well they perform.
performance wise they are about the same (the 7950GT might even perform better) but the truth of the matter is that you will want a DX10 card and also from what I have heard the 7950GT is the biggest power hog out there among video cards.
No way 8800's beat the crap outta the 7950GT even my GTS is better than the 7950GX2. There newer unified shaders DX10, and there great OCers even with stock cooler.