For a 800W, you better be doing 2x5850 CrossFire. My question is, why is the PSU relevant in a PC designed to play WoW? The GPU will be the deciding factor here.
Also, do note, wattage != quality. It's the quality of the power the PSU can provide that matters. For PSUs, stick with Corsair, PC Power & Cooling, XFX, OCZ, Antec, and Seasonic.