XWindowSystem > XFree 86
XFree86 is obsolete. It was the main X-Server until Debian 3.1 (sarge).
It was replaced by Xorg in Debian 4.0 (etch).
XFree86 is an implementation of the X Window System written originally for the Intel 80386 platform and certain video cards used on that platform. In short, it forms the basis for the Graphical User Interface of Debian (DesktopEnvironments). Today it supports other platforms and many different types of graphics cards. If you cannot find a specific driver for yours, use the VESA like default.
As root user, run:
(see dpkg manpage).
This will present you with a wizard for configuration.
After installation run
(see startx manpage).
Documentation is located here: in your Debian documentation under /usr/share/doc/xfree86-common and /usr/share/doc/xserver-xfree86, or on XFree86 homepage.
See also : XStrikeForce