Things to keep in mind for gaming

:
-You'll have to run windows to play all the variety of games available
-Get windows 7, because DirectX11 gives much better performance to multicore systems (Check WoW forums to see how to make WoW
use DX11 instead of openGL, or DX10, it'll give u better performance)
-The 5870 is a must, because its 70-100% faster than the 5770. And don't get 2 5770 because their slower to = than the 5870.
-Cpu clock speed is important, the higher the better, so get the 3.2Ghz
-Don't buy ram from apple, get only the 3Gig and buy more ram from newegg (it'll cost half the price)
-Get the Quad core 3.2Ghz because the 6 core is over kill. Im not sure about this but maybe you can add another 3.2Ghz later if you
want to have 2 (8 cores).
-If you want an SSD, DONT BUY IT FROM APPLE. You can get one from Crucial or Kingston for less. Currently Crucial is selling 256GB SSDs
for 620$ & 600$, so two of those are cheaper than 1 512GB from Apple. Plus Apple doesn't sell 256GB SSDs (according to what i can find
on their site). And both companies give you a 3year warranty on their SSDs for FREE.
Check out this site to compare benchmarks for CPUs, GPUs and SSDs.
http://www.anandtech.com/bench/CPU/2