Ken I don't disagree, Nvidia cards are overpriced. But in the case of the 8800GT can't you actually find it for $250? I'd have to check but I think it's sold for around that.

Why Nvidia over ATI, well it's subjective really, most benchmarks are close to a tie, and when it comes to overclocking I can't say that Nvidia's better than ATI. One thing they've been doing better than ATI for games is driver optimization. That could change though.