(This post assumes computer literacy -- if your familiarity with computers extends to "the Yahoo" and "the Google," you probably won't get much out of it.)
I've always been a Microsoft guy. Sure, I was an early adopter of OS/2 back in the day, and over the years I've had some Unix experience, and nearly everyone I love is a Mac user, but it's always been DOS and then Windows for me. Ultimately, it comes down to thoroughness of documentation.
Macintosh has historically been a completely closed platform. Growing up, I never understood how it was possible for someone who wasn't an Apple employee to become a Mac developer; it seemed like there was 1 Mac programming book on the market for every 200 Windows programming books, and that 1 Mac book was always out of print. This was prior to mass adoption of the Internet, too, so newsgroups and wikis weren't available to help. From the perspective of a young coder looking for a place to hang out, MacOS was a boarded-up storefront guarded by smelly homeless dudes, and Windows was a rockin' nightclub full of hot chicks and no bouncers.
To add insult to injury, Mac users tended to have this bizarre chip on their shoulder about the technical inferiority of Windows. "Everything good about Windows was ripped off from the Mac," they would sneer. The fact that there was some truth to this claim made it sting even worse.
Now that the last two years have seen an unprecedented explosion in Macintosh popularity, it's time to hoist those bastards on their own petard.
Imagine what the reaction from the Mac community (and the Linux community -- if Windows were black, Slashdot's logo would be an animated GIF of a burning cross) would be if Microsoft released their next-generation operating system, and it was just their own GUI shell running over Linux. Sure, there would be a few proprietary libraries and API shims to ensure backward compatibility with existing Windows apps, but the "next generation" was just their own frosting applied to someone else's cake. It would be like the end of the Cold War. Open source had finally torn down the Berlin Wall, and the evil empire of Capitalist Coding had finally collapsed under the weight of its own technical inferiority. Goateed graphic designers would be dancing in the streets.
Make no mistake, this is exactly what Apple did with Mac OS X. They scrapped decades of intellectual property (in both hardware and software!) in favor of becoming a game company, which is essentially what they are now. They produce one game, called "Figure out how the fuck to make Linux usable, with maybe some neat translucence effects." They finally wrote that Flight Simulator interface for the Mach kernel that the prepubescent blond girl was navigating at the end of Jurassic Park.
And yet, all this has only increased the Mac cachet. "Everything just runs so smoothly on Mac OS X," people marvel. Yeah -- because somebody else besides Apple wrote the operating system! It's a lot easier to use an existing threading model to write a responsive GUI than it is to implement your own preemptive thread scheduler.
Apple's decision to take this route should provide some insight into what a clusterfuck of spaghetti code the real MacOS kernel must have been. When it costs more money to simply document and improve your existing product than it does to throw it away entirely and prettify someone else's, you know you have an absolute cesspool of technical inferiority on your hands -- a coding abortion clinic.
The one consequence of the increase in Mac popularity that I absolutely can't wait for is the corresponding proliferation of Mac-only malware. Another historical shoulder-chip with the Mac crowd has been, "At least with my Mac, I don't have to worry about all the viruses and Trojan horses and spyware that you Windows guys do." Yeah, that's because malware authors tend to target platforms with more than eight users. Nobody's ever written a virus for IBM mainframes, either, but it's not because OS/390 is such a great operating system -- it's because there are only a few thousand IBM mainframes in the entire world. As soon as Mac OS X hits the 10% mark of consumer OS market share (which I agree they probably will), we'll see an explosion in Mac-only viruses, and it'll be as devastating to that market as tuberculosis was to the Aztecs. Merry Christmas, Symantec!