I have recently been setting up an old PC as a backup system for my office enviroment. However 10 year old hardware does have it's limitations so I had to go through a few hoops to get it to my liking.
  1. Install latest Debian as Ubuntu got a little upset with the old BIOS and disk drives
  2. Make sure that the system has sshd installed, i.e. apt-get install ssh
  3. Stop the graphical login running by executing update-rc.d -f gdm remove
  4. Install xfce4 (it uses less resources than KDE or GNOME), apt-get install xfce4
  5. Make xfce4 the X window manager by creating a file ~/.Xsession with the line 'exec xfce4-seesion'
Now you can log onto the Linux console and type startx or use a remote X server display, e.g. X11 on OS/X using ssh X tunnelling. e.g. ssh -X -l <userName> <machineName> When using a remote X server there can be problems if you do not start some programs in an X term displayed by the X server and for which you started your X tunnel. e.g. xclock does not care, GNUCash crashes the X server. So make sure your X server displays an X term of some description.