An IT department's consistent preference for Microsoft Windows over Apple's OS X and, as a result, of any PC over a Mac is to me, the ultimate illustration of their lack of understanding of their users.
I've recently played around with Windows 8, and was a Windows 7 user. This is the key difference, to me:
An IT department want features, control and access to the system to tweak and play around with. Technology is central to their objectives. Windows offers this level of control to them;
users just want tools that function out of the box and allow them to do a better job in the same or less time. Technology should be unobtrusive and get out of the way of production. Mac OS X offers this to them.
Making an abstraction of the differences, with all respect for each side which has his or her arguments all lined up, business should ask themselves the question: are we an IT business or are we a user business?
Are we about achieving results or about being a fertile playing ground for IT?