I would get the 670 or 660ti. Just a personal preference for me. Nvidia has more features like PhysX, TXAA, adaptive Vsync, & 3d vision. But if you do want AMD there is an amazing sale on a 7970 that comes with:
DiRT Showdown, Deus Ex, Nexiuz, Total War: Shogun 2, Battlefield 3, and Sonic Generations. All for $369. Hella deal!
Also the Zalman Z11 Plus looks kinda expensive for a case, i would recommend the Coolmaster Haf 912. Its only ^0 and it give you a lot of space and is very sturdy. It is kinda big for a mid tower as it is very wide but i like it. It also is very rugged as the review that made me want to buy it is someones's gf went ape *** on their comp with a base ball bat and hit it 5-6 times, and he said the case was strong enough that none of his parts got damaged. http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Also i dont think you need a 750 watt, a 650 should be good as the ivy bridge uses less wattage and if you go with the GTX 670 FTW it also is low wattage. So i have both of those and 650 watt is working fine for me and my friend said i can do double sli with it too. So unless you are getting a really watt heavy cpu cooler or triple sli/crossfire i would say you are fine with a 650 Watt