Just recently I upgaraded my veteren biege G3 running at 266Mhz with a Sonnet 1000Mhz card which has added a bit of sparkle to my computing. I continue to use OS 9.2.1. I also have a second back up HD installed, But my thought is that now with the machine running fast enough to upgrade the OS, I might load the second drive with OSX and then swap around when I need to use older software. Is this possible or do I need to use a partitioned single HD? Any thoughts?