I don't know about Bob but you can leave Window ME and Windows Vista out of this conversation if you expect to remain FRiends.
XP, however, is another story. You can mention that all you like, XP was the perfection of the user interface, the challenge they said was insurmountable when talk first started of introducing computers for the home. XP was the final perfection to all that fiddling in 95, 98 and 2000.
Actually, XP is NT 6.0. Win2K definitely shows itself as NT5 in the folders.
I've used NT since 4.0 and never had any of the problems people complain about with 95, 98 and ME.