The cold hard facts are that MS has it's OS and software installed on over 96% of the world's PCs.
Oh it really gets tiresome hearing that statistic. I believe symbian are actually the most installed OS full stop, not that they will last long now either.
The battle of the OS's has only just begun, the new playing field is mobile devices which msft are going to lose, i guarantee.
Mobile devices ARE the future of personal computing, and there are MANY more mobile devices than PC's.
If you thought msft were safe, think again, the next few years are going to be very interesting indeed, and the outcome may come as a surprise to those not blessed with foresight.