I'm one of those folks who takes unbelievably good care of their machines. The ol' iBook gets a magic eraser and polish every couple of weeks, the display gets wiped down frequently, and I blow the dust out of the PowerMac once every two weeks. BUT Yesterday, I decided to unplug everything and really give the PowerMac a real cleaning. I blew air in the back towrd the front, through the heatsink toward the back, underneath the heatsink and all over. Now - the key is - run hot water from your tap over the canned air canister you use and it turns the can into Turbo Air™ I got out about twice as much dust as usual, and my CPU temp dropped 15 degrees Farenheit. Love your Mac.