Unable to boot into 10.4 installation disc I'm attempting to fix my friends old iMac G5 running OSX 10.4. There are a bunch of updates she needs, but she doesn't know her admin password. I'm attempting to reset it with her 10.4 install disc, but when I attempt to boot into it, the machine just runs and runs and runs and never seems to make it to the installation screen. I thought maybe it was the disc, so I downloaded an ISO of 10.4 and tried to boot into that, but that didn't help either. OSX seems to recognize the discs when I view it's contents in the folders, but booting into them just don't seem to work. Should I try booting from a USB version?

I wanted to show her what Ubuntu might look like (so she doesn't have to pay $200 for Leopard, the last version of OSX her iMac will support), but booting into that LiveCD fails too.
Most PowerMacs can't boot off of USB drives natively. They can boot off of a FireWire drive, however. If you have an external FireWire hard disk handy, you could try using Disk Utility to clone the 10.4 boot disk onto the drive and booting off of that. There is also (supposedly) a way to make the system boot off of an external USB disk, but it involves editing an nvram variable. This article explains how to do that.