between those 2, i7 is a no brainer, 2 cores vs 4 cores hm....

now with that said, all you want to do is play WoW, now i can't say for 100% sure hes playing on epic settings, but I build a exact replica of my computer for a friend ( i don't play WoW so i have no idea)

mines a i-3 3.2ghz, 4gb ddr3 ram, and Gforce 6500, spent less than 550 on everything in the tower. and it runs WoW just fine, Tho im not sure how extreme his graphics settings are.

I run deskspace 3d desktop 24/7 tho with no problem. only real thing I can think of that works out my graphics card. only games I play are diablo 2 and wc3, and I have 6x diablo 2 bots running right now and can play wc3 on full video settings, with the d2 bots running, but all that put together might not even equal WoW lol.

So i guess what im saying is you might be spending too much money for what you want. look into it