I recently bought an iBook G4 with OS X 10.5.8 from a friend (my first Mac). It seems the short username is 'new owner'. I was going to change it to my name by following these steps [System Preferences - Accounts - Click on lock and input password - right click main account - advanced options - change short user name] mentioned here. But i am also reading in several places that this could be dangerous. Apple also seems to advise against it. Your thoughts and advice would be very welcome. Many thanks.