While criticizing Microsoft for a lack of innovation is certainly mostly legitimate, think of how cleverly they implemented the progression from DOS/Windows 3.1 on the front end and Win NT 3.1 on the backend to today's (virtually interchangable, from a high-level development perspective) Win2000 and WinME.
This is in stark contrast to the nightmare that awaits Mac users with OS X. I like lots of parts of the Mac user interface, but I find myself gnashing my teeth every time I use a Mac (for example, the machine in the corner of my office right now) because, while I'm using Fetch to FTP a file up to a server, I can't do anything else substantive in the foreground due to the piss-poor multitasking. I feel like I'm running Windows for Workgroups again...
On the other hand, obviously Unix has optimal stability, but the world's worst user interface. I've been pretty skeptical of Apple's ability to reconcile these two extremes, a view that is greatly supported by this article on The Challenges of Integrating the Unix and Mac OS Environments.
Particularly good is the explanation of how resource forks are kludged in OS X, in a way that's going to make filename extensions on DOS look like rocket science. But I digress. Please feel free to forward your pro-OS X flames.