I have Kubuntu 11.04 installed on my laptop, and I want to try, and probably switch to, Gnome-based Ubuntu. What is the best way to do so, by using the package manager, and not overriding the installation? I tried it before, but every time I had unwanted leftovers - The welcome or shutdown screen didn't change, dangling packages remained, etc.
For generality, the question goes also the other way around: How can one replace the KDE-based distro with Gnome, without any leftovers?
Is there a systematic way to completely replace Kubuntu <-> Ubuntu, and make sure that the only remaining things are the home partition?