Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
I don't know what steps you took to 'erase the whole drive myself', but usually that error is because the system detects that it's installed already.

From the Leopard disk, at the beginning of the install there should be an Options button somewhere. Click on that and select "Erase and Install". This will wipe the entire drive and allow you to install.

Failing that, to eject the disk from the drive, shut down the Mac. Put your fingers on the trackpad button and press down then turn on the Mac. Keep holding the button down until the Mac spits out the disk.
 
I don't know what steps you took to 'erase the whole drive myself', but usually that error is because the system detects that it's installed already.

From the Leopard disk, at the beginning of the install there should be an Options button somewhere. Click on that and select "Erase and Install". This will wipe the entire drive and allow you to install.

Failing that, to eject the disk from the drive, shut down the Mac. Put your fingers on the trackpad button and press down then turn on the Mac. Keep holding the button down until the Mac spits out the disk.

Thank you for your reply. A PRAM reset did the trick.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.