Purchasing: Does this contract mean we can omit buying OS's for new hardware the university buys?
No. Microsoft's licensing of its desktop operating systems is such that you must still acquire a fully licensed copy of Windows when you buy a new computer. Essentially, you cannot omit the OS from any machine you purchase, nor receive credit from Microsoft or its distributors as a result of the MSCA. You can, however, upgrade any copy of an older OS under the new MSCA.
This rule does not hold true, however, for the applications covered by the MSCA.