I remember getting the first iMac, Bondi blue I believe it was called. Running OS 9 I believe, or 8.5 at that time. Got the next release of the iMac in white/clear after that which is the first computer I had to run OS X. I had to upgrade to a whopping 512 mb of RAM just for OS X to run smoothly. Constant dual booting as OS X looked great but was not a lot to do with it at first. How quickly that changed!
I recently have been marveling at the iMac G4 and what a design feat that computer is. I thought I had thrown my broke one out but found it hiding in the back of a closer. I am thinking it needs a new power supply and will give that a try at some point when I have more time. The computer on its own though is simply amazing. That neck is so solid and still so smooth. I really do wish they brought this design back. Make it so it supports a 24" screen and fit all the Mac mini specs inside and you have a really versatile powerful little computer that was a great crossover in design and function. When I have someone in my office and want to show someone something on my computer I keep wanting to reach out and just swivel the screen over to them, but alas it is planted on the desk!