Gnome is the default desktop environment for Ubuntu. For people who prefers using KDE as the default desktop environment, Kubuntu would be an ideal choice. But how about people who need both?
Actually it is pretty easy to have both Gnome and KDE on your machine. You could install Kubuntu on top of Ubuntu, or likewise Ubuntu over Kubuntu.
There are multiple ways to achieve the above objective. Some people might prefer using aptitude (due to better un-installation capabilities) and some prefer using apt-get from the terminal. As for me, I chose synaptic as the installation medium.
Launch synaptic (System > Administration > Synaptic Package Manager)
Make sure you have the latest package information. Click Reload if not. You are also advised to use the nearest local/regional mirror or internal repository mirror if you have one.
Search for kubuntu-desktop package
Select the kubuntu-desktop package and mark for installation
When prompted for package dependencies, click mark.
Click ‘Apply’ to start the installation process
Click apply to confirm the installation
The installation process will start right away
During the process you will need to specify the default desktop environment to be used as default environment for your account. Select gdm if you want to use Gnome or kdm if you prefer KDE.
To change your desktop environment to KDE, logout your current session
Select ‘System > Quit’ and choose ‘Log Out’
Once logged out, click Option > Select Session
Then choose KDE and click ‘Change Session’
Fill in your username and password to log in. You will now using KDE (Kubuntu) as your desktop environment.