WoW utilize CPU more than GPU in some sense, by up to three usable cores. get a decent quad core CPU with high clock speed and get last 2 gen enthusiast level graphic card to run this optimally on Ultra.

iam using i5 750 @ 3.3Ghz with good ol' HD 4850, playable on ultra but i like my fps running on an orgasmic 1xx FPS so i run it on good with DX9 setting.

overkill, just get a quad core i5, you wont be using the HT anyway unless you are working and using HT heavy application. Sandy Bridge is good now as it can be clocked near average of 4.0Ghz on the fly easier than previous generation (quad core) hence better response. your spec is at the rooftop, and why settle for 4GB of ram when you can easily set up 4Gb X 2 since the price is damn low now.

Current Gen price will drop continuously due time, Sandy Bridge has mature enough that the price is competitive. But do not hope that Intel going to slash their prices anytime soon. If you cant wait, buy it now. If you have the patient wait until AMD release their bulldozer to the mass public and do a straight out comparison, bulldozer slated to release somewhere from September to November is few phases.

i believe somehow lower than Sandy Bridge of the same level. Wait for Dozer to come out and scourge some Sandy's i5 quad core.