OK, I went ahead and bought the dual 2.5 GHz G5. The price was just too good. NOW, anything I should do in particular to monitor the cooling system, aside from looking for leaks? You really can't see much without taking off the CPU covers...
Also, in days past you could add AppleCare to a system with an expired warranty by having an Apple dealer inspect it first. Can someone confirm this is no longer the case?