Gnome and KDE..
Confuse to choose what backtrack desktop that would be used?
Nowadays, Gnome and KDE is the most popular X-windows for most linux user.
For those who don't know. Gnome and KDE is a GUI (Graphical User Interface) or in other word, desktop environtment that make the user easier to interact with Linux. In fact, linux can be used without X-windows, but that will make you face black and white text interface to interact with linux.
X-server not only consist of Gnome and KDE, there are lot of it such as IceWM, XFCE, Blackbox, Fluxbox, etc.
Important to be known, GUI or X-windows in linux is different from Microsoft Windows GUI.
In Windows, the GUI is included in its main system. as the result when the GUI in windows crashed, the main system also crashed.
Thats the difference, in Linux, the GUI runs above the X-window system, so when the GUI crash, the main system didn't crash too. To resolve it just restart its X-window environtment and you will get the GUI back in action.