The i7 is a waste of money. The only difference between it and the i5-3570k is that the i7 has hyperthreading, which games don't use. (Which means there's no reason for a gamer to buy an i7.)
Get the extreme4 - it supports future crossfire, among other things.
I'd get a seasonic or one of the more expensive lines of Corsair; that's actually made by a different company and isn't an amazing PSU. (But 750-800w is the sweet spot to power two high-end graphics cards and the CPU, both overclocked.)
Other than that, you have one beast computer, my friend - this is going to serve you well. I have only two recommendations:
1) Spend the little extra money to get a 128GB ssd. (The Vertex 4 is the best value wise.) It makes a HUGE difference as to how fast your computer "feels." (And if you play MMOs, installing them on the SSD completely gets rid of loading times.)
2) Just as a matter of personal preference, check out as a keyboard the Microsoft Comfort Curve 2000. It's really well built, and easy to type on. It's also the only keyboard I'd recommend or use that isn't a mechanical board.