The last Windows versions my parents actually used was Windows XP, maybe they encountered Vista somewhere for a brief moment. In my capacity as the family sysadmin, I've switched them to Linux around this time. Ubuntu first, now Debian. XFCE back in the day, Gnome3 since a few years. I think they'd hardly recognize a modern windows installation any more. Gnome3 has it's warts, but I really hope it's here to stay, at least in the broad strokes of the UI paradigm.