Welcome-- the GTS burns 100W, i think, and the gts burns 160.
I love giving advice

even if it may not be of the expert variety.
I personally would go for one 8800gtx for now as it would be cheaoer and can deliver more performance than you could possibly use with less power draaw, less heat produced, and less quirky issues resulting from SLI which is still immature. Then later down the road, when you can afford it, grab a second one for a real screamer!
If you're going big, though- definately don't go for the 320 MB version of the gts-- just becasue you have two doesn't mean you're working with double the memory, and you'll have spent a lot of money but will still be somewhat limited in the future with demanding games.
I also might go for 2*1GB of faster ram instead of the overpriced, quite slow 2*2 GB ocz Gold- you might find stability issues, but more importantly, you'll be limiting your overclock with it. (sorry- i guess not with the 680i as it unlinks)
And if you're going for SLI for sure, I would choose the evga 680i- some people here will argue with that

, but it's the best SLI board out there.
Oh- and not to sound like a parrot, but SKWAK- get a new psu
edit- oh just saw your second post