I work at NASA and have many university colleagues I work with as well. A recent IP survey I had IT do at GSFC in MD showed a Mac OSX installation base of about 30%. This is similar at my freind's universities... at least in the physics and engineering depts. We recently moved our 20 or so PC's over to Mac a few years ago and have been very happy. I was able to show I saved the government approximately $60K-$90K a year in gained productivity and reduced IT support, salary, etc.... So, while Windows is used mostly now by the Best Buy consumer level base, which is 80% of the "market", the professional technical use of OSX is much higher. I suggest having a mix of new machines if possible and taking your own data. Track how often the machines are used, under repair, software costs, and how the students take to them and make your own conclusions. Good luck.