Edgy's support ended in April of this year. It was not a long term release, so
it expired after two years. I advise you to download the latest version 8.04 and
install it. This is far simpler than to do upgrades through all of the
successive releases. You cannot skip releases. Ubuntu or Kubuntu 8.04 is a long
term support release and the desktop version is good for three years and five
years for the server version.

You can get Ubuntu here: http://www.ubuntu.com/GetUbuntu/download

Get Kubuntu here: http://www.kubuntu.org/download.php