If you have access, look at it over the last 6-7 years, it is brutal. Make sure you get installed rather than sales, MS keeps commissioning reports that somehow manage to not count Google, Facebook, Baidu, Tencent etc etc's servers. Not sure why though.
I can name a few possible scenarios, and I'll let you decide:
- Ballmer had a notoriously short fuse and the company would rather pay for what he wanted to hear, not what they needed to hear.
- Gartner, Forrester, et al were a bit intimidated by the piles of bodies in the C-level offices with gunshot wounds in them, and they liked the money.
- Microsoft-commissioned reports aren't intended for market research, but rather publicity and their own marketing purposes. They don't publicize the ones they commission for actual research, because it's not pretty (especially since Windows 8/Server 2012).