Ubuntu has Gnome as the default desktop manager but there are others also available. A desktop manager provides icons, windows, toolbars, folders, wallpapers and abilities like drag and drop. The X Windows Systems (Unix-like systems) are more flexible and typically consist of a window manager such as Metacity or KKWin, a file manager (Konqueror or Nautilius), a set of themes and programs as well as libraries for managing the desktop. Other desktop environments that can be installed on an Ubuntu system include KDE, which is far more configurable and complex than Gnome, XFCE, which is a lightweight desktop environment more suitable for old PCs and others.

Before installing one or more alternative desktop environments, you have to add the universe repository to Ubuntu. You may skip this step if you have already done it.

- Go to System / Administration / Software Sources. When launched, the tool will present you with a dialog which allows you to easily check the boxes or even change your download location. You might want to check every box that is checked, so you won't have to do this again.

Installing KDE

The KDE desktop seems to be a little more familiar to windows users so using it will be a little easier for new users that just switched to Linux from Windows.

To install KDE, open a terminal and type:

code $ sudo apt-get install Kubuntu -desktop

Reboot the computer and at the login prompt, select Options / Sessions and pick KDE from the list. The rest is up to you. Enjoy!

Installing Xfce

Xfce is a very lightweight desktop environment, based on the Xfwm file manager. To install type the following command in a terminal:

code $ sudo apt-get install Xubuntu -desktop

Installing Enlightenment

Installing it is just as easy as installing KDE or Xfce on an Ubuntu system as its packages are available in the universe repositories. To install Enlightenment, open a terminal and type:

code $ sudo apt-get install enlightenment

Several mouse+key combinations are available for various actions. For instance, middle click on the desktop will open the Enlightenment menu, middle click + Alt will open the task list menu, middle click + Ctrl will open the desktop menu and so on.

Installing Fluxbox

Fluxbox is a highly customizable, very fast and quite pretty window manager. However, Fluxbox is all about minimalism and is definitely not for everybody, but it's as lightweight as it can get, so it's probably very useful for low systems.

To install it, first make sure you have the universe repository enabled, then open a terminal and type:

code $ sudo apt-get install fluxbox

Installing Sun Looking Glass

Project Looking Glass is based on Java technology and it contributed to the open source community by Sun Microsystems. The project brings innovative 3D features to the desktop environment. The desktop interface offers an intuitive, new 3D environment to interact with desktop applications featuring window transparency, rotation, zoom and so on.

There are 3 LG3D repositories: stable, testing and nightly builds. You can use any one of them but it's highly recommended you use the stable one so you won't get into any troubles.

Open the /etc/apt/sources.list file with your favorite editor and add the following line at the end of the file:

code deb http://javadesktop.org/lg3d/debian stable contrib

Install LG3D using the commands:

code $ sudo apt-get update

$ sudo apt-get install lg3d-core

After the installation is complete, log out from your current session, click on the Options button, select Project Looking Glass and login as normal.