I'd upgarde to Corsair 500R case.\the 300 is a bit small and while decent cooling for a single OC'd GFX card, I don't put 2 in those boxes.
I'd use a 750 watter (Corsair TX or XFX Core Ed) of not doing any serious OC'ing....If going tot he max on the CPU and twin OC'd non-reference 670's, Id want Corsair HX or Seasonic X series, 850 watter.
With IB, the 212 is a bit light, it's big brother the 612 will get ya 5-7C more cooling on IB.
Consider Newegg, Amazon, or a Cooler Master Elite 431 (using right now and keeps my cards nice and cool with three added fans). 750+ watts, Corsair is a good brand. Keep the motherboard and processor, even if someone tells you different. It's a great bang for your buck. Even I'm using it. Aside from that, I think it's good. For the gaming keyboard, check out Razer and Logitech, they're stuff is pretty good. Been using Logitech keyboards for years and Razer seems to have a good build quailty that I can see.
But again, I like it a lot. No, I love it. And if your happy with it, then get it. But PSU is a bit weak for SLI mode in my opinion. You might go up to 800+ even. Best of luck to you though. ^_^
The only difference between the extreme4 and the extreme3 is the number of SATA 6/b ports. Unless you plan on using more than two hard drives save your money and pick up the extreme3. There aren't a lot of reviews on the extreme3 for the fact it's only been out on the shelves now for less than two weeks.
OCZ has one of the worst if not thee worst reputations as a company in general. The only reason you keep seeing OCZ Vertex on here all the time is becuase this board is full of sheep who seem to forget how OCZ has put the screws to their customers in the past including their gaint dud SSD's aka OCZ 3's. People on here have a bad habit of buying into the Kool-Aid. This SSD down below utilizes SF Toggle NAND and it's not only solid, it saves you $20.