Hi all, I have a three-year-old iMac 2.15 GHz Intel Core 2 Due with 2 GB of memory. Running OSX 10.4.11 I started having problems where it got increasingly slow and eventually wouldn't boot. I kept wiping the internal drive and reinstalling the software and it would be OK at first but eventually would get slow again and refuse to boot. Took it to the Apple Store and the guy seemed sure I had a bad internal hard drive. So I bought a 1TB Toshiba external USB 2.0 hard drive. I was hoping to install the system software on it and boot from that drive so I wouldn't have to hire someone to install a new internal drive (I tried taking an iMac apart once before... never again!) I formated the external drive choosing the option for Intel-based iMacs (BIOS? GIOS? something like that). It then showed up as a bootable drive and I installed the system software on it. However, my computer refuses to boot from it. When I hold option as the computer is starting, it doesn't show up as an option for booting (only the internal drive and the system CD show up). When I select it as the startup drive, either in system preferences or having booted from the CD, I click restart and it simply boots from the internal drive despite the fact that I selected the external drive (the internal drive is now working again temporarily because I once again installed the system software on it from scratch). When formatting the external drive, I will at times choose journaling and at times not, and the same thing with case sensitive, but it doesn't seem to make a difference. Also, I don't think I've ever managed to boot from the external drive, but it's a little hard to tell since both drives have the system software installed. I assume if I see an icon in the dock from a program that exists on the internal drive and not the external, that means it booted from the internal drive. Any ideas? Thanks!