Looks like a great (albeit expensive) build! 1200W is unnecessary unless you plan on getting at least two more GTX 580's down the line. Of course some will say just get the 2500k but if you have the cash, the 2600k is faster (even in gaming). Just not by much. The Corsai Vengeance is a great choice in memory!
Its gonna be a fun build, just make sure you have a good step-by-step guide and follow it closely. You don't want to forget to plug in the 8-pin cpu power cable and then panic when it doesn't post!