Macs are great if all you want to do is work related things. Recently macs have been getting more games but overall they still are not the best platform for gaming. If school is his primary concern then macs will do.
Linux is not an OS I would recommend to a student or even a gamer. It's fun to play around with but overall it's not something I would like using every day.
Windows is probably the best bet for a student/gamer. It receives all the games and has a plethora of school/work office apps like Word, excel, etc...
Me personally I went to college with Windows on my machine. It worked out great too. LAN parties were a breeze because 99% of the guys who I went to school with primarily used Windows as well.
As to the stability of Windows...I've been using Vista for two years now and had no problems at all. Supposedly Windows 7 is much better than Vista as well. You've got to realize that Windows has like 90% of the PC market - that's millions of PCs. You're obviously going to hear more horror stories about windows crashing then a mac or linux. There are just more out there.
But anyway, my first choice will always be Windows when it comes to gaming, school or work on a PC. Then a mac which as I said is fully viable for a student when it comes to school or work but it lacks in the games department.
And as for Linux, it's great that it's free but I can't recommend it for school or games.