Razer does not manufacture or design headphones, those are rebranded chinese imports. I'd rather use headset from some reputable audio hardware manufacturer than overrated mouse manufacturer.
More cores does not help WoW or any other games in any way. Problem most people are having is old inefficient quadcores or even dualcores. This year's 3GHz dualcore CPU has ten times the power of 3GHz dualcore from 2004.