Ursprünglicher Beitrag von: afusz ,
It depends when you bought it. Some PBG4's came with Panther (OS X 10.3), most came with Tiger (OS X 10.4), although it is capable of running Leopard (OS X 10.5). To find out which one you are running, see Tyler Bly's Answer. (Go to Apple Logo in upper left hand corner and select About this Mac from the drop menu).