Go with the 7900GS, it'll go right over the top of the 7600GS...
even look at Tom's Video Card Charts!! BTW, I've got a 7900GS and I'm really diggin' it. Just wish I would have been a bit more patient and picked up a 7950GT, but oh well!
The BFG Tech BFGR7950256GTOCE GeForce 7950GT 256MB is available on newegg for just under $200. Lifetime warranty and it comes overclocked. However, these cards are not DX10 but I don't really see that being a problem as software has not had a chance to take full benifit of the new instructions.
I have a 7950GT 512 and its pretty solid. It gets the job done for most games that I play. I bought this knowing the 8800s were coming out but now I'm glad I did. I'll probably wait around for next gen cards to come in before I upgrade.
Your friend is wrong. Go with the 7900GS. You may even find the x1950xt below $200. It will beat up the 7950GT but from the 7900GS and up you will do well in most current games unless you play at high(er) resolutions.
Yes, the 7950GT is a great SINGLE 512MB card, but one thing you have to understand is that the onboard ram is only used for to store things like textures, once you have stored them, remaining space will not net you any extra performance. The difference not only lies in the pipelines (which after reading a review somewhere between I think a 6800, 6800 unlocked and a 6800GT it clearly states that even though there's a performance difference, it isn't all that great), but more importantly in the Core. The 7600GS uses the G73 core which is based on the G70 core, but of course... crippled. On the other hand the 7900GS is based on the G71 core, an improved revision for more performance. There's really no point in even comparing them because you'd be comparing the GF7 cheap mainstream (7600GS) to the GF7 cheaper high-end solution (7900GS), kind of like comparing an 8600GT to a 8800GTS.
Another thing, do not SLI unless you're going to SLI the BEST (and I mean the absolute best) cards on the market (i.e. 8800GTX), not even the 8800GTS is worth using SLI. Using SLI is strictly reserved for those who want the best performance that money can buy, not for those who are wanting to use 2 midrange solutions.
For example, the 7600GS 256MB is about $75 in newegg and you'll find the X1950Pro for $135 in the same website. However, if you SLI two 7600GS you'll only see an average increase of 120%-130% from this card's solo performance, however the X1950Pro (Same price as 2x 7600GS) will perform roughly 200-220% faster than the dual card setup. And this trend repeats ALWAYS no matter which cards you choose, this is why SLI is only used for systems that are intended to be the best of the best.
And it makes it's bottom hurt too, the onboard memory thing is from a time that long forgotten when not many had access to hardware and we thought that more onboard memory equaled performance but that's false.
The core is the most important part of a graphics card and probably going after an 8800gts 320 is the best choice.
And like javimars said it will just do terrible sexual things with an 7950gt