funny .. many many different perspective from different groups of supporter.
None is wrong IMHO.
If you put yourself as a non-IT geek, what Peter2 says is totally sensible. A normal person going to work just want to use tools that is familiar and easy for them to use (without learning curve as much as possible). Most of the time, it is the user power that pushing what the IT department will deployed, and from what I have observed, if the it IT department or some "brilliant" folks push their wish to user, a lot of time there will be back-fired and application adoption rate will be poor. Even with higher management push, it also mean a lot more support calls.
Open-source is great, I do use it, but for some application, it just work in Windows environment better especially office and collaboration tools. But it is not without bugs. Then again .. Open source equivalent has its own fair share of bugs and some can be as irritating as the proprietary ones.
I see hordes of opensource supporter, nothing wrong but opensource do have its fair share of issue and I will say majority of the world populate are non-Geek. They just want to use something that works without the need to tweek, mod or call supports. Seriously, I have personally use Ubuntu as desktop and also Windows. Ubuntu still need a fair share use of command-line occasionally to make things work and default installation is also as bloated and its hardware requirement does not really means low.
Seriously, I still feel open source linux interface design by geek for geeks. A different perspective as for Mac and Window (Except Metro)