A neighbor of ours was moving and had stack of crap she was throwing away / giving away. One of the items was a ~3-year old Dell desktop — one of those ugly grey and black towers with the meaningless names (OptiPresidioFlexron 3000 or something.) It had XP Home on it, and she thought the motherboard was bad or something. Really, it was mostly just too slow to be usable and she had a new laptop anyway and just wanted rid of it. She gave it to Tammie, and I figured I’d take a look at it and replace the MB if necessary. After booting it into XP, it didn’t look too bad but I really didn’t want an old Windows box of mysterious provenance on my network, so I wiped and repaved with Ubuntu current. A wireless USB NIC and 15-minute driver hunt later, we have a perfectly adequate 2nd websurfing desktop in the house— total out-of-pocket cost: $20 for the NIC.
Never trust an operating system.