A friend of mine just gave me her old G4 desktop that has long been nothing more than a doorstop. It is currently running 10.3 and I would like to upgrade it to 10.5 using my leopard install disks. If I just put the disk in and turn it on it wont boot, and if I double click and go to the installation program from inside OSX it prompts me for the administrator password. My friend got the computer from her father years ago and neither her nor her father can remember the password on the machine.

Is there a trick to boot from the DVD or at least to format the drives so I can install Leopard?