Update the repository lines in /etc/apt/sources.list, apt-get update; apt-get dist-upgrade. You need to be root for all of those, or use sudo. There's also the update manager GUI that's probably installed in your X desktop. Just exist the Myth frontend, hit escape till it asks you and say yes, and look around in the menus. I don't know where it is as I prefer the command line version. <br>
<br>The Myth Wiki has database backup info. You just dump the data to a file. Do this before upgrading. :) <br><br>You shouldn't need to re-install or anything drastic like that. I've jumped a couple versions of Ubuntu with no ill effects. All the Myth stuff upgraded just fine for me. <br>