i used 5 wow-instances on one pc with 2 gb ram - entering sw made my pc almost freeze and my hard drives nearly exploded - uses process explorer, i saw i had only 50 mb free memory left - so i think he tried to use the swap on my hard disk - atm i'm using 2 pcs, also i'm getting 2gb ram to add them to my main pc, maybe it works with 4 gb and a new xp with 64bit support