Install Ubuntu desktop:
1. #sudo apt-get install ubuntu-desktop
2. also change "gdm"
3. remove Kubuntu desktop
#sudo apt-get remove kubuntu-desktop kubuntu-artwork-usplash
This command remove some programs, but command "autoremove" remove all programs
#sudo apt-get autoremove
4. Restart X-server
Install Xubuntu desktop:
1. #sudo apt-get install xubuntu-desktop
2. change "gdm"
3. See point 3 and 4 from "Install Ubuntu desktop"
Install Kubuntu desktop
1. #sudo apt-get install kubuntu-desktop
2. change "kdm"
3. #sudo apt-get remove ubuntu-desktop
4. #sudo apt-get autoremove
