Well, the ISS is older than XP so I'm not surprised that it was upgraded to XP sometime later.
and the Computers that run the station's critical systems are 486 based. whats your point?
I guess this is the only COTS product on board.
I maybe mistaken it might be a 286 or 386. But it's a special radiation hardened chip by Honeywell. They were originally designed for Space Station Alpha and were a carry over to the ISS.