Warren, I'm sure you saw this, but just incase:
http://www.olinux.com.br/artigos/393/1.html

"Unfamiliarity, compatibility and the time/effort needed are the main obstacles. Linux is a 'rawer' computing experience that requires learning. The rewards are there, of course. Compability with Microsoft Word is a problem because that program's everywhere. In so many schools they're just trying to keep what they've got working and there's no time or resources for trying out something new."