However, there are differences that have nothing to do with user interface design choices such as toolbars (or lack thereof), keyboard shortcuts, etc., etc. One of the biggest differences between the two platforms is fonts, but more specifically, font rendering. If you've used Windows for years, one of the first things you'll notice as you start using Mac OS X is that things, e.g., web pages, look different and indeed it's not just your imagination. It turns out how Apple renders fonts is different than how Microsoft does it on Windows:
I became acutely aware of the latter back in 2007 on account of noticing that the Windows version of Apple's Safari browser made pages look different than what I had been accustomed to while browsing with Firefox and IE (before I stopped using it years prior).
Turns out, now that I've had a Mac for the past year, I've reached a point where I prefer browsing on my Macintosh vs. my Windows system because of this font rendering difference (how pages look).
While I would agree with Spolsky that Windows' fonts are easier to read, the difference isn't stunning. Text is clear on the Mac. It's just that Windows uses less anti-aliasing and the pixel contrast, i.e. the individual pixels that make up a single letter, is more pronounced on account of the jaggies. Spolsky also writes:
you'll find that most people don't really know what to choose, and will opt for the one that seems most familiar.
Iterating, after actively using Mac OS X for a year, I now prefer browsing on my Mac. It's created a bias that I would have to say, if I bought a laptop today, it would be an Apple Macbook. (Aside: The Mac I got 12 months ago is a Mac Mini).
While font rendering is subtle, since it is visual and vision is people's primary sense, it's a major anchor for ensconcing people into a comfort zone. And since people are wont to resist change, it's very hard to pry them away from said comfort zone once they gravitate to it. This all means that people dropping Windows in favor of Macintoshes aren't likely to come back anytime soon. As a bad portent for Microsoft, check out the following AppleInsider article that came out last month (Nov. 2011):
In summary, PC sales dropped double digits in both the UK & Germany and close to 10% in France. But if companies selling PCs in Europe are blaming the global recession, the Macintosh market for Apple in Western Europe grew just shy of 20% year over year. I'll also remind the reader that Apple charges a premium for its hardware.
In closing, while I very much still use Windows 7 on account of Windows Media Center and my XBox360 acting as my DVR (check out the latter video link), nowadays if I'm browsing the web, more than likely it's on an Apple device (my Mac, iPad 2 or iPhone).