The 8800GTs are sold out everywhere because they are a mid priced card that is pushing speeds up there with the 600 to 800 dollar cards. It's a much better card for the money if you can spare the extra 50$ or so.
Dollar for dollar, you can't beat it. It's like buying Axioms!!
Experimenting with dual cards gave me improved but limitedly improved results in all but the most taxing of 3d loads. Start with the 800GTs and then when you decide that you need to try make Crysis look even more pretty you can consider adding a second card. Although I understand there is no PC/video system in the consumer realm yet that will play the game smoothly at it's highest settings so....
