As a technology professional, I'm often asked (sometimes goaded) to weigh in on the Mac vs PC debate. I've never owned a Mac. I've tried them, and I just don't like them. I'm a Windows guy.
I run a Windows network for a living. I grew up with Windows from Windows 3.1 to the soon-to-be-released Windows 7. When I bought a computer for my house it was a PC running Windows. When I bought my wife a laptop it was a PC running Windows. So, people often expect me to be a Mac-hater, and while it's true that I wouldn't want to buy one for my own use, I actually think they're pretty amazing machines with a really, really good operating system.
See, Apple has positioned themselves as sort of the Rolls-Royce of the personal computing platform. They only sell very high-end, high quality computers and charge a premium price for them. Microsoft has recently released a series of adds about how you can get a Windows laptop or PC cheaper than you can get a Mac, and this is entirely true. The reason for this is that Apple refused to sell cheap components slung together in hap-hazard fashion.
Apple is a hardware company.
Microsoft is a software company.
The cheap computers aren't made by Microsoft, but by Gateway and HP and ASUS and a host of others, who simply install the Microsoft operating system. Microsoft has put a lot of time and effort into making sure that, as much as possible, their operating system runs on any hardware on the market- including the Mac. Apple sells hardware and includes their software as a value-add. Their software only runs on their hardware (legally, anyway) and they like it that way. You'll never see Garage Band or iMovie for Windows, but you do see Office for Mac.
But here's the real kicker that no one talks about. 85% of Mac owners also own a PC according to a recent survey by the NPD Group. Just like (I'm guessing here, since I'll probably never fit into the category first-hand) most Rolls-Royce owners also own some sort of lower-end car. So, when someone says "I'm a Mac." they're probably really saying, "I'm a Mac and I own a PC." At least 85% of them, anyway.