OK, my OS became corrupted (10.5.6) and my sound device disappeared from the system. I had no audio, and it was causing kernel panic on startup, everytime. I swapped out my 7200rpm drive back with the original Apple supplied 5400rpm. I purchased a 2.5 USB2.0 caddy. Can I install 10.5.8 onto the drive in the caddy (7200rpm) when it arrives, and will it reinstall the missing sound driver?