Ask Dan: Two 7950s or one 8800?

I'm in the process of buying a new computer, and I have come to a crossroad with video cards. I cannot determine if I am better off getting 2 Leadtek PX7950GT 512mb cards and running in SLI or getting 1 nVidia 8800GTX 768mb card.
What would your recommendation be? Will I get greater performance in games running 2 cards? Or is it better to just get one top-end card?
Jason

Fortunately, the rat's nest that is video card comparisons has become much simpler these days, which makes it very easy for me to answer your question. No, just kidding. It's as bad as it ever was, if not worse. Fortunately, it is possible to convey some vague idea of the current state of play without presenting you with 108 graphs of benchmarks from different games at multiple resolutions and with and without different levels of anti-aliasing.
There's no real-world situation I'm aware of in which a single GeForce 8800 GTX will be slower than a pair of GeForce 7950 GTs
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