1) games are most of the time hard to run in linux, even a popular game like age of empires was tricky (but possible).
2) regulations state that the OEM is sold to one mobo.
meaning that if you change the motherboard, you need a new OEM copy.
thus calling to microsoft is useless because its a new motherboard...
BUT since it's a computer from school, i would try to get a special deal through the school, it may have a special deal with MS and you always have www.MA3D.com