MACDef - OSX runs a different window manager, Aqua, which I would imagine is much less stable then the core OS. So when Aqua freezes (Which will be rare, yes), most people will just reboot ther computer. Same thing on Win2k - most of the time when it freezes it is just the GUI that does so, and if you can telnet into the computer, you can kill the offending process and not have to reboot the computer.
As for OS9, sure it is reasonably stable when set up perfectly. Again, this isn't something that most people have the luxury of having. I have used Macs for work, unfortunately most of them have had the unfortunate problem of only having 64MB of ram, and no matter how much I messed with the settings, I couldn't even make them reasonably stable running OS9 (I downgraded to 8.6 and it ran better). On the G4 400/128MB, things ran a good bit smoother, but again, stability was a moderate problem (Similar to Win9x with 128MB, much worse on the 64MB machines). Also, if you are having problems with an extension, it can reduce your system's stability drastically. I don't use macs a lot, but in my experience I like OS8/9 the least, would take Win9x over them, would take OSX over WIn9x because of stability, and like Win2k most. I am also a much more efficent multitasker on Windows because I am much more used to all of the commands, and the environment. So, while I am not the last word in Mac use by any means, but I am more experienced on Macs then most people, I can comfortably use OS9 without getting too confused
Anyway, lets not make this a big battleground, if I really want that I can go post on Arstechnica, although it has been a long while since I have done that.