At my school all the computers are running Windows XP with IE8. The IT tech hates it but there's not much he can do about it. He does make sure that all updates (that are needed) are applied, and he's locked down things that are not needed. All the students laptops that we get are running Windows 7 64bit (new students get 64bit, mine is 32bit) including the teachers laptops, the exception being those students in the Graphic Arts programs, they get Macbook Airs. Of course the Windows laptops are POS HP620's with Celeron Dual cores and 4GB ram.
As for this guy charging a tax, it's BS! All he needs to do is stop supporting IE7, on the popup tell users their browser is no longer supported and provide links Google Chrome, Firefox, IE9, and Opera. It's a rather simple solution, my colleges website (used for submitting assignments, and taking exams in class) tells you if your browser isn't supported and have links to supported browsers. There for a while FF wasn't supported because of all the new versions that were coming out one after the other.