Yes, but the MACs are on the move.
I hear several success stories of companies swapping out entire windows machine parks to MAC, and getting less expenses on support, generally more performance. Main motive for changing from MS to MAC may have been the fact that MS decided to terminate XP support and at the same time enforcing Vista as the "new and improved" replacement. Windows7 may save lots of market shares for MS. Restoring support for XP may further enhance MS market shares. Who knows? But people are getting more aware nowadays that older MS operative systems does not work so well with more than 2 GB memory in the system, and people tend to a higher degree want 4 GB+ of memory in their PCs nowadays. Maybe the enforcement of Vista on the market did MS a big misfavor in awakening people to the fact that MS does not so well support large memory banks. Also, the fact that MS does not so well support 64 bit CPUs prior to Windows7, and that many people has been using 32 bit XP on hardware that is really 64 bit dual core machines for some years now, will make people less wanting to use MS operative systems.
Now people are getting aware of that the most stable and supported platform running their office applications, (and with a higher performance than MS platforms), is the MAC. This will make new installs of Windows7 suffer.
So, unix is the way to go, and nowadays it is merely a question about if the performance and configurability of a Linux OS outweighs the administration cost, compared to the MAC.
I guess MS will have to market their own unix-based OS, or take a Munchausen grip in the proverbial own hair and lift their OSes above the performance now available in unix OSes.
Things are evolving pretty fast. Take a look at the premium OS for the late 80s, the VAX/VMS 4.7 with all its robustness and configurability. It is today suitable for embedded applications like mobile phones and ipods, looking at its capabilities.
I would certainly want VMS in my mobile phone. It would be a robust and lean platform, and i would be able to run several phones in a cluster, and seamlessly hotswap my calls to the phone currently working the best. Gee! I would even be able to swap the CPU out for a new one in the mobile without dropping any calls!
But seriously, Nokia is just about releasing their N900 mobiles now, to compete with... MS Mobile? Mmm, yes, to a degree. But rather be competing with Apples products. The Nokia N900 with its linux OS Maemo will certainly get their market shares. Because of many reasons except having something faster, more stable, and with more features and applications than any MS mobile platform.
So maybe now it is the time for UNIX to take over the market, both in small and large platforms.