Ubuntu 8.04: Upgrade or clean install?
 

Which path should you follow? Should you take advantage of Ubuntu's package manager and use it to upgrade your system to the latest 8.04 Hardy Heron release, or should you download a CD or DVD ISO image and do a clean install? Common wisdom says that doing a clean install is the better, safer course of action. There may be a little extra work involved configuring everything once the latest and greatest is installed, but that's nothing compared to the pain of an update gone wrong, according to traditional thinking. But that cautious approach may no longer be necessary.

I did a clean install of Ubuntu 8.04 recently on my development machine. It was a quick and easy process. I backed up the data and configuration files residing in my /home directory, installed the new release, then copied my saved data back in place. Nothing to it, and everything worked when I was through.

http://www.linux.com/feature/134517