The Bottom Line: I had a smooth upgrade experience, much better than Windows, with no software reinstalls, or rummaging around for drivers or passwords. Software Update briefly torpedoed my Internet connection, but another upgrade install of Leopard solved the problem.
My copy of Leopard finally arrived Saturday morning. I got home from work around 3 and had a couple of hours to install 10.5 before meeting friends for dinner. I've got a 1.42 GHz G4 Mini with 1 GB of RAM. Things went smoothly after I figured out where my wife had put my copy of Leopard. The installer reported that my upgrade install would take 3 hours and 47 minutes. 5 minutes later the remaining time was listed as 2 hours and 11 minutes. In actuality the install took about an hour and 45 minutes, considerably slower than the 30 minute times people with Intel Macs were reporting. Leopard finally booted up, along with all my settings, files, and previously installed software. My wife was yelling that we had to leave. I verified that the wireless Internet connection worked and shut down the machine.
I didn't get back to Leopard until Sunday afternoon. The Software Update immediately came up and offered me a Login and Keychain update and an Apple Remote Desktop 3.2 Client update. Did I need the latter? I glanced at "recommended for all users" in the explanation field and pushed the install button.
The Mini rebooted and I noticed the wireless Internet connection was gone. I checked System Preferences and found that the AirPort card was listed as disconnected. I clicked the Turn AirPort On button and Leopard started scanning for networks. 20 minutes later Leopard was still scanning and the AirPort card still showed as disconnected.
So I did another upgrade install of Leopard. This took another hour and 45 minutes, but restored my Internet connection and seemed to put everything right. Had Leopard overwritten the updates that had knocked the Internet? I ran the Software Update and got a message that all my software was up to date.
