But Windows becomes less usable even if you do nothing but run the same single program over and over.

I guessing you meant "stable" rather than "usable" (cos it's kind of hard to see how a system couple become less usable by running an app multiple times).

If you are taking about Win95/Win98/WinME then I absolutely agree with you, they are all festering heaps of old junk. We started of with a poor base and just kept adding layers of crap.

However, exactly the same can be said of MacOS < 10. I used to manage 200+ Macs and their installs degraded in exactly the same way Windows did before it became a "real" OS. Just using them hard day in, day out would leave you after a year or so with a subtly broken OS install that needed reinstalling (as did the Win9x boxes and to a lesser extent the NT4 ones).

Win2k and WinXP are good, solid, stable operating systems. As I am sure MacOS X is also, it looks like an excellent bit of kit.

When it comes down to it I choose my OSes for the task they are suited to and for the software that is available for them. I use Linux for my DNS/mail/static web servers; because it just works and if something is broken I know 99% of the time that the breakage is sitting in a plain text file, wating for me to fix it.

I use Win2k for my webserver that runs my dynamic web pages; because I want to write them in ASP and ASP.NET, as that is what I do for a living.

I use Win2k for my desktop machines because they are stable and they run the software I need; VID, VS.NET, Word, Excel, PowerPoint, Project etc

I use WinXP on my laptop because it does everything Win2k does for my on my desktop, but also suspends and resumes at a break neck speed.

If MacOS X had the software available that I use everyday then I would probably take a serious look at it, but it doesn't. Unless there has been a dramatic change over the last three years the version of Office for the Mac is not as good as the Windows version, because it is slower and less stable. And the chances of the development tools I use becoming available on the Mac are very slim.

For the same reasons, although I love it so, I would never dream of running Linux on the desktop. It does not have, and is never likely to have, the software I require in a desktop enviroment.

I salute all you MacOS X users, keep up the good work...