Ubuntu Dapper to Edgy upgrade...

Using apt-get

Edit your /etc/apt/sources.list as root. Change every occurrence of dapper to edgy.
Use any prefered editor. If you have a CD-ROM line in your file, then remove it.

sudo vi /etc/apt/sources.list
or
use the following Simple command

sudo sed -e ’s/\sdapper/ edgy/g’ -i /etc/apt/sources.list

Now you need to update the source list using the following command

sudo apt-get update

Upgrade using the following command

sudo apt-get dist-upgrade

Double check your process was finished properly using the following commd

sudo apt-get -f install
sudo dpkg --configure -a

Now you need to Reboot your machine to take your new ubuntu 6.10 installation to effect all changes.
Have great fun with your new Ubuntu Edgy Eft

Other useful links:
http://www.ubuntuforums.org/showthread.php?t=227052
http://ubuntuforums.org/showthread.php?t=285304
http://www.debianadmin.com/ubuntu-edgy-upgrade-common-problems-with-solutions.html
http://www.desktoplinux.com/news/NS3291004537.html