Locking ... I think everyone's had a chance to make their argument, and this is just turning into a flame-fest at this point.
The fact is, these cards have VERY different architectures, not to mention both gpu makers (nV especially) work with game developers, which leads to code that favors one brand over the other at times. So there's a huge degree of variability in perf betwixt nV and AMD when you look across all games, settings, and resolutions.
The best way to decide which to get is to look at as many benching sites as possible, focusing on performance at the resolution you want to play at, and on the games you want to play. If it's of major import to you to be able to 'max' a game, then you should also pay attention to the settings the review sites use.
Sometimes, YES, they are biased (sometimes accidentally, believe it or not) and will choose games and/or settings that favor one company over another. That's why you should check a whole bunch of sites and never rely on any single one.
I consider [H] to be one of the most reputable review sites, personally, and LOVE their 'max playable settings' reviews with the fps-per-second graphs, because you can get Avg FPS comparisons from like 50 other sites. Their benches provide a unique and meaningful perspective, IMHO.
Something else to keep in mind re: the two brands cards, and that's 'features'.
To it's advantage, AMD has Eyefinity (basically much better multi-monitor flexibility) and Morphological AA which allows AA to be 'forced' on pretty much any game. nV doesn't have an equivalent of it yet.
nV cards OTOH support physX, have much better 3D support, and support more gpu-accelerated non-graphics apps (such as video transcoding) through CUDA.
This is just stuff off the top of my head, I'm sure there's many other features that are unique to each brand's cards.
Lastly ... for all the talk of nV's supposed 'cheating' upthread, I would point out that evidence
suggests that AMD 'cheats' with it's Crossfire implementation, achieving their much-balleyhooed 'better scaling' by coding their drivers to allow considerably more microstutter than nV does with their drivers.
IOW, neither side are exactly 'angels' ...Edited by brettjv - 10/29/11 at 11:46am