Should schools/ universities use commercial software?
If only the commercial product has the features the course NEEDs, then yes, of course. (But one vain professor's "need" is another's ego trip. It is amazing more Washington politicians don't emerge from Academe... there's plenty of politics played in the ivory towers.)
But I've seen a teacher struggling in a physics class for 15 year olds because the fairly trivial thing the teacher wanted the kids to put into their spreadsheets had to be explained three separate ways to accommodate the three different spreadsheets in use in the classroom... is this sensible use of teaching time? Mandate OpenOffice across the school. If the kids (or Dell, etc) can persuade the parents to pay for Excel, too, well at least the school isn't to blame.
As for the "discounts for education", surely everyone sees what's going on there?
One reason little of the money I give to charities goes to schools is that I see how they waste what they have.