You'll have to update /etc/apt/sources.list to reflect the sources of the new repositories... With that said, this method doesn't tend to work very well on Ubuntu systems; many users have dependency issues and whatnot when upgrading, and it becomes a big hassle.
The officially-supported method of updating an Ubuntu system is to use update-manager, which supposedly takes care of all the problems that could be induced by using dist-upgrade. If in doubt, look at their website page: http://www.ubuntu.com/getubuntu/upgrading
On the software updater (update-manager) it will say at the bottom that a new release is available and you can choose to upgrade. DO NOT an edited sources.list then use dist-upgrade, it tends to break thinbgs
Yeah, it may be better to backup your files and Gconf, then do a manual reinstall via CD.
The dist-upgrade method messed up all of my default programs (on Feisty).
do you have an UbuntuForums account?
You'd benefit, its a great forum.