This is a strange question, but it's really important. If you install Mac OS X (Tiger we'll say) onto a HD, you are able to put it into various Macs and they will boot from it just fine. Does Mac OS 9 work like this? I was helping someone with an old 8600 (with G3 processor upgrade) that had a 4GB SCSI HD with Mac OS 9.1 installed. I removed this HD, hooked it up inside a Power Mac G4 (Quicksilver 933) and cloned it to a 60GB ATA HD. I used Disk Utilities "restore" feature to clone the drive (while booted into Tiger located on another 80GB HD), which worked just fine. However, the computer WILL NOT boot from this Mac OS 9 drive. The classic feature works just fine inside OS X (except it suggests I update it to 9.2), but it won't boot from the 9 drive for anything. Mac OS 9.1 shows up in the startup disk preference pane, but if you select it and restart, it boots back up in OS X. Holding down OPTION on reboot, only shows the Tiger OS X HD. Anyone have any ideas? I have to help this person again and would like to resolve the issue. Thanks!