If you have an old computer, here's what to do:
1. Find a tall building with a window, preferably on the top floor.
2. Throw your computer out of said window.
3. Enjoy your new computer!

I'd run an Ubuntu Server on it and use for testing, still have a Pentium 4 with 512MB RAM and 80GB HDD with Ubuntu Server, too bad I don't have enough space in my room to put it and use, but I recall once installing Mandriva Linux on it and it turned into a beast after being a slow ass turtle on Windows XP lol

I would keep it in a showcase almirah or safe somewhere else, I have b&w CRT monitor and those heavy cpu cabinets with floppy drive also, surprisingly in working condition with DOS. I remember having to copy paste NES games from one pc to another when I was young. I'm definitely not throwing away one unless it caught fire or broke and is total waste.

Well..... the first step should be check integrity of your last backup