Remember the newer spec xbox 360 with the Jasper chipset has a different power supply to the original 360. just make sure you get the right one or it may go boom.
how do i tell the difference?its a couple of years old so i assume it'l be the older type?
Just looked into it, apparantly they are different sizes, so they wont fit into the xbox if its the wrong type, so I dont think you can do any damamge, just the expense if you buy the wrong one from somewhere that wont accept returns.