Quick Question about WoW.
 

http://img472.imageshack.us/img472/949/mainmenu3pj.jpg

I bought my brother WoW for Christmas & he's been playing non stop ever since. (xmasgrin)

I am also upgrading his computer from left over hardware from my recent upgrades.
In WoW, do I need to back-up anything just in case his HD takes a nose dive in the upgrade process?
Does all his progress get saved on Blizzard's server or on his Hard Drive?

Just want to be on the safe side as he's invested alot of time playing.

Re: Quick Question about WoW.
 

Don't worry, all MMORPG's save our characters and data on the server end, feel free to smash the HDD with a hammer if need be, as long as you have another one. ;)