KDE 3.5 for breezy

To update your KDE to the version 3.5 you have to add the suitable repository to your apt sources.list. Since the packages are signed you first have to add the key.

wget http://people.ubuntu.com/~jriddell/kubuntu-packages-jriddell-key.gpg
sudo apt-key add kubuntu-packages-jriddell-key.gpg

Then:

sudo kwrite /etc/apt/sources.list

This will open your souces.list with kwrite. Add the line:
deb http://kubuntu.org/packages/kde35 breezy main to the list, save it and close kwrite. Then type into your konsole:

sudo apt-get update
sudo apt-get upgrade

If ever you have problems with dependencies, use adept: Full Upgrade --> Preview Changes(NOT Commit Changes!) here you can see which programs would be removed and you can chose if you want them to be removed or not. After you've made sure not to remove important things (like your kubuntu-desktop) except they will be replaced by a newer version, click on "commit changes".