I'd go for X58 (I guess P55 is ok also though) and the i7.

My opinion, and I am sure many will disagree, is that for wow only (as its coded for 2 cores max) processor speed is more important then the number of cores. And at any rate, even 10 boxing the bottleneck is never the cpu, its the SSD to Video Card that slows everything down.

An X58 motherboard and even the 920 i7 should be more then enough (unless a faster i7 is available for a little bit more cost).

Money should be spent on the video card ram (more the better 1G is minimum) and on the SSD.

8G with a 64 bit operating system should also be good enough, although no doubt more is better.

I have a revo SSD drive coming Ill report the results in dala soon enough, to see if I am right as I have a 3.2gHz duel core cpu.