My dad laughed when I said I still use a 2006 ThinkPad daily, then he admitted his shop still runs on Windows XP
He came by last Saturday and saw the old thing sitting on my desk, and after he stopped grinning he told me the whole back office at his work never left XP because the inventory software won't run on anything newer. Made me wonder how many of us are quietly keeping a whole system alive just because one program refuses to move, so what's the one piece of old software you can't ditch?