Recently I've had some discussion with colleagues about Mac OS X, Windows, and Linux in comparison to each other. Generally, I've found that most people agree that Mac OS X is more stable than Windows, and those that are familiar with Linux feel that it too is more stable than Windows. But after that being said, they come back with an apology for Microsoft stating that they (Microsoft) have to get Windows to run on fragmented hardware, whereas Apple standardizes the hardware and can therefore provide a more stable operating system for it, because there aren't nearly as many variations in hardware configurations.
I agree that Apple definitely has an advantage because of the consistent and standardized hardware platform to run on. Windows does have an enormous amount of Intel hardware that it must run on, so the argument I commonly hear is that Microsoft can't possibly run consistently for each separate hardware scenario, and that this causes instability issues.
While this may be partially true that Windows needs to run on a wide variety of hardware, I often ask how Linux can effectively run on the same hardware set as Windows, yet run consistently better than Windows. The main reason in my opinion is the enormous amount of community effort that goes into the Linux kernel and the GNU/Linux operating system as a whole, giving it the ability to quickly and efficiently adapt to the ever-changing hardware. Microsoft with its limited amount of employees that contribute to its own kernel, can't possibly keep up as everything is kept behind closed doors. While keeping its software proprietary will help Microsoft retain its grip on how Windows is distributed and ensure cash flow inbound, it ultimately hurts the Windows consumer with the limited amount of community resources that Microsoft has to put towards it. The amount of community support for the Linux kernel is virtually unlimited, however even Linus himself has made comments in the past about the amount of work to keep everything in line with the current amount of contributors.
There are many other debates on this subject, but it's interesting to hear the different takes on why people feel the way they do about what operating systems they have used. Personally, I don't feel any need to apologize for Microsoft. Microsoft has capitalized significantly over the decades due to its model of marketing software for generic Intel hardware. But in today's world, things are changing and the variety of hardware is far greater than it was 20 years ago, not to mention the rate of change as well.