I couldnt agree more with this build, great cpu/mobo/ram everything. Admiral helped me with my build not too long ago and it was about the same budget, I took his exact build except for the case cuz I wanted a different style. Do you already have an operation system? if so that can give you an extra $100 to play with.
I agree with welshmouse, Wow isnt a very GPU intensive game. If thats all hes playing then you should suggest down scaling some parts and putting that extra money to say......his Wow account so you can play longer? lol Because this build can handle some of the recent games ok but it is a little overkill unless he really wants dx11 for some future game or something.