If you really want the best, then you should wait until Intel fixes the P67 boards. Buy a i5 2500K. Don't buy any other cpu, expecially an older i7 because their slower in performance. The i5 2500K(4cores) @ stock settings matches the i7 980X (6cores), and the i7 980x costs 1000$. You can find reviews on the 2500K online that confirm this. BTW WoW performance is affected by cpu frequency so, you can overclock the 2500K to get more performance, especially since its easier to overclock the 2500K than any other cpu ever before. Most ppl have gotten at least 1GHz more out of it @ the stock air cooler.
Heres a link that will tell you everything you need to know about WoW performance done by Tom's Hardware. It will confirm everything im telling you.
http://www.tomshardware.com/reviews/...ance,2793.html
Now regarding the motherboard. The best ones out there are the ASUS P8P67 OR GIGABYTE GA-P67A-UD3. You can try finding these in store, but most computer stores dont carry many highend boards, and they also overcharge like crazy. Your best bet is Newegg. Don't be intimidated by the bad reviews, most of the ppl who buy from there don't even bother to post if they've had a good product. Plus Newegg's has the best services with defective products (inclusive), unlike any store can offer.
Heres a link for ASUS's new EFI bios, this make overclocking and doing other things in the BIOS super easy and simple.
http://www.youtube.com/watch?v=NEMDscJyHew
Now for the RAM, this will be a little tricky. Right now you can get 4GB for a very decent price. Really the ram you choose doesn't matter that much as long as its not value ram (aka low quality ram). The tricky part is that the quality (speed) of the ram will affect your overclock ability. Generally the higher the speed the better the overclock ability on the 2500K. Id recommend that you first buy the cpu and the mobo and then focus on the ram (because these are more important). But heres what id recommend.
http://www.newegg.com/Product/Produc...82E16820231444
If you have the money, then go for
http://www.newegg.com/Product/Produc...82E16820231434