Back when I first began with computers, I bought a second-hand IBM machine that had Windows XP on it, and what a nice machine it was, too.... a matt black beauty with a front panel that in some ways resembled a radiator grill.
Anyway, it developed some issues that I could not fix myself, only being very new to computers, so I took it to what became my fave PC store for many years. To cut a long story short, Pat [the store owner] restored the machine to its former glory with OS2 as the primary OS. Apparently it was there the whole time.
The previous owner had put XP on a different drive but didn't dual boot for some reason, so I was oblivious to it until Pat discovered it on the original HDD. I ran that machine with OS2 for about six months, but sadly, I wanted a faster and more powerful machine, and the IBM wasn't up for an upgrade, so I foolishly sold it to buy a new machine with a dual core Pentium P4 that, at the time, was blazingly quick.
I regret selling it now, cos I'd love to be able to tinker with it, etc, but sadly it's gone forever, ne'er to be seen again. The person I sold it to went on to also sell it, but to an unknown person, so who knows where it is these days ... if it even exists still, given that was like 20-ish years ago.