Neverware’s CloudReady can turn an older computer into an extremely useful device by installing the Chromium OS. It basically turns that doorstop into a Chromebook or Chromebox.
To get started you need any desktop or laptop computer with 2 gigs of RAM although some may not work fully. Check the CloudReady Certified Hardware list. If your hardware is not there don’t worry it may still work. There is a paid version for schools, organizations and companies but the free version works just fine. As a matter of fact the free version does one thing the paid product can’t. You can dual boot it with Windows.