kubuntu-desktop -- This is the recommended metapackage to install; the full Kubuntu installation, with all the Kubuntu recommended packages.
sudo aptitude update && sudo aptitude install kubuntu-desktop
If you later decide you don't want KDE any more, go back to the terminal and paste in sudo aptitude remove kubuntu-desktop
The default can always be changed later by modifying the /etc/X11/default-display-manager file. For KDM, the file should read /usr/bin/kdm; for GDM, the file should read /usr/sbin/gdm
First you need to edit the /etc/apt/sources.list file
sudo gedit /etc/apt/sources.list
add the following line
deb http://ppa.launchpad.net/kubuntu-members-kde4/ubuntu gutsy main
Save and exit the file
Update the source list using the following command
sudo aptitude update
Install KDE 4.0 in Ubuntu
First you need to remove any exiting kde4 using the following command
sudo aptitude remove kdelibs5 kde4base-data kde4libs-data
Now install kde4.0
sudo aptitude install kde4-core
This will complete the kde4.0 installation
/usr/lib/kde4 and can be installed alongside your existing KDE 3.
Remove previous KDE 4 packages, they are not compatible (apt-get remove kdelibs5 kde4base-data kde4libs-data)
Add deb http://ppa.launchpad.net/kubuntu-members-kde4/ubuntu gutsy main to your /etc/apt/sources.list
Install the updated kdebase-bin
Install kdebase-workspace kdebase-kde4 kdebase-runtime, note that PPAs aren't authenticated so you will likely get a warning when installing
KDE 4 apps should appear in your KDE 3 K-menu or you can run a full session by selecting "KDE 4" from your login manager.
To avoid having to start a second X server for a full session install xserver-xephyr and run Xephyr :1 & export DISPLAY=:1; xterm and run startkde in the Xerphyr xterm.