It depends upon what you want from your computer.
Do you want it to be a means to an end, or an end in itself.
I use MSOffice at Work as that is what work supplies me. If I had a Windows box at the moment it would have MSOffice on it for familiarity.
As I use Mac OSX at home then has iWork on it instead.
Whenever anyone of my non-technical friends asks what to load on there PC, I ask them
What are you familiar with?
and say there's your answer.
Invariably they then end up getting Windows box from Dell or the Purple Shirt Brigade, which works for them, and saves me getting phone calls.
Whilst Schools, College Universities churn out Windows Educated students then business will use Windows as is what requires least effort for the MAJORITY of users.
Linux may be free to buy, however it certainly isn't free if you then have to spend time and money training everyone.
In a commercial environment then you can't get away with saying that waiting on answer from a forum from the linux guru who knows the answer but is offline and not sure when coming back to you.
This is why Ubuntu and Red Hat are doing well as they offer commercial level support with SLA's. However that support ain't free.
There is plenty of place for Linux (I just wish would standardise, however I ain't holding out any hope) Windows and OSX, however it really isn't worth the argument with someone prepared to start an article on the internet about it.
Pick what suits you best and get on with it. If someone else prefers Windows that is there choice, it suits there needs. Same goes for OSX, (you really know you don't want to argue with them

)