Use Xubuntu or Lubuntu on old computers/pcs with limited resources

If you have an old computer with limited resources you might have problems to run the recent Ubuntu releases 12.04 LTS or 13.04 smoothly. If so, I recommend you to use the derivatives Xubuntu or Lubuntu that use much less resources. While Ubuntu 13.04 is said to use around 320 MB RAM, XUbuntu 13.04 and LUbuntu 13.04 are said to use around 160 MB and 103 MB respectively.