One of the computers at my father's job is still running Windows 3.11 for Workgroups. It's a prebuilt from Escom with Intel 486, 256MB disk, not sure about RAM, and combined with HP Deskjet 510 printer. The only thing it needs from time to time is to replace the CMOS battery and unclog the ink cartridge (there's a bottle of liquor right next to the printer). It's used almost daily and has outlived several generations of other PCs in the office.
If it's never powered down then it should be fine. I've seen a computer in telecom center with a disk spinning for almost 20 years. One day power failure occurred and UPS failed to kick in, disk stopped and when the power came back it failed to spin up again.
