From the beginning of time... well since Ubuntu 6.06 I have done a clean install whenever a new release of Ubuntu came out. Yes it was a little time consuming doing a complete backup of the home directory, installing the new version and then restoring the backup. But it was enjoyable to me (a geek thing I suppose) as it was almost like a renewal or something. Logging in the first time after the install and exploring the new features... and then re-installing all of the applications that I use.

Follow up:

Well with the release of Jaunty Jackalope, I decided I would try to do an upgrade on my workstation. I do a backup of my home directory nightly (who doesn't) but being a little anal I tarred my home directory to another drive anyway. Wow, a 140.6GB tar file. What do I have in my home directory.

Sometime after I installed KDE 4.2 I was messing around and installed some application and then decided I didn't like it so I uninstalled it. Something got confused and I ended up breaking Plasma. I am hoping this upgrade will fix that.

A couple of days before the release of Ubuntu 9.04 I downloaded the kubuntu-9.04-rc-alternate-amd64 ISO image as I planned to do the upgrade earlier. I didn't really want to burn a CD so I found an Easy way of Mount/Unmount .iso Images in Ubuntu. I installed gmount-iso and it worked like a charm. (yes I could have used "sudo mount -t iso9660 /home/jim/temp/kubuntu-9.04-rc-alternate-amd64.iso /cdrom -o loop" instead) I opened up a command window, moved to my newly mounted install directory and ran sudo sh ./cdromupgrade and selected the option to download the latest updates.

A couple of hours later and my machine is now running Kubuntu 9.04. It appears only the installed packages were upgraded as it didn't fix my Plasma problem. No worries, I think I have figured out how to determine what to reinstall. I also need to install the 9.04 version of VirtualBox. Everything came up ok and appears to be working and it took less time obviously than it would have if I had done a clean install.