Install KDE 4.1 on Ubuntu 8.10
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 intrepid main
save and exit the file
Update the source list using the following command
sudo aptitude update
Install KDE4 desktop Environment using the following command
sudo aptitude install kubuntu-kde4-desktop
Enter your password and press Y when asked if you want to continue.
Configure kdm, KDE's graphical login manager screen. Press Enter.
Here you need to select which desktop enviroment you want to use as default on for Gnome select gdm and for KDE select kdm select ok and press enter
This will install all the required packages for KDE4
Running KDE Session
After finishing installation you need to logout from your current session.In login window click on Options---> Select Session...
Select KDE click on Change Session
Select your option here you want to run just for this session or default Desktop Environment
KDE 4.1 is loading
KDE 4.1 Desktop