I've always recommended people get a good PSU, but that thing is obscene. Way overkill. You should be spending less than half that on the PSU.
Extremely unlikely there will a difference between the i5-3570k and the i3770k for gaming, although that's a good price on the i7.
The 680 GTX is only marginally better than the 670 GTX. Definitely not worth the extra $100 IMO, although I understand the desire to get the fastest single card possible. Still, a 670 GTX averages greater than 60 fps on max settings in 1080p on Battlefield 3, which may be the most demanding game available. So I don't think you could possibly notice a difference between the two cards anytime in the near future.
I also think those $200+ mobos are a waste of money, but that's just me.
Overall, I thing this is a bit overkill. For a lot less money you could build a machine that performs almost identically. The ONE thing I would recommend upgrading is the SSD. Games will quickly eat up a 120 GB SSD. I would go with a 256.