I agree. I run on Linux for my own personal use these days (though I do still have to boot into windows for a couple of Windows applications for my work), but my family is die hard windows only. I've recently started converting them to limited user accounts as I format their systems to repair the terrible damage they've done to them. My father, who's been using computers for around 25 years now, is the only real holdout I have who refuses to use a limited user account.
The only problems you might run into is a lot of windows applications insist that they need administrator access to run properly, so be prepared for an onslaught of dealing with this. It's especially bad if your users are on something like Windows XP, where it's not as easy to elevate the privileges temporarily. For instance, my mother uses a loan processing/origination software for her work called Calyx Point. In XP it does not run on a limited user account by default without messing with the registry and permissions of the directories. Same deal with a lot of games as well. When I setup my nephews PC I put him on a limited user account on his windows xp system, and when he wanted to start playing Diablo II, I had to do some searching to figure out just what I had to change to let it run on a limited user account.
I haven't had these limited user systems up long enough to really see a noticeable difference in if the systems get as fouled up, so it will be interesting to see. I did use all my normal security settings and programs on top of the limited user accounts. Hopefully this will keep my family from trashing their computers twice a year. I'd suggest trying the same thing.
Of course if they don't have to have windows, by all means stick them on something like Ubuntu, just be prepared for all of the "Why can't I see the dancing bunnies?!" questions you'll get heh.