I'm a PC user, and I prefer Windows to Mac OS. Just personal preference, nothing more.
I've always hated when I run into Mac snobs who talk down to me as some "uneducated" person because I won't jump ship.
Fair enough.
Unfortunately, it is far more likely to run into an "uneducated" than a reasonably informed. Along these very lines, I had an interesting discussion with my Nephew in 2007 at his sister's wedding, where he expressed distain for Macs, because as a Comcast ISP installer, their various internet configuration settings could only be done at the Terminal's Command line.
After I fell out of my chair in shock, I pulled up the System's control panel for Network settings and ran though a bunch of the Ethernet options, showing him that there was an alternative to the Command Line. His revised statement: "Our Employee training at Comcast sucks", and he was going to go tell his coworkers that they had been killing themselves by trying to do it the hard way.
These ads speak a partial truth. It is way less expensive to buy a PC over a Mac.
Agreed...partially

The problem is that even if we agree that a PC has a lower initial purchase price, that fact doesn't also guarentee us that it will end up having a lower total lifecycle cost too.
As such, while initial purchase price can't be ignored, its not the only cost factor to consider.
I also agree that if you want to do gaming, your options on a PC are way more open than on a Mac.
No argument there.
I think of a Mac as a specialty computer. Kind of why you buy an espresso machine as opposed to a normal coffeemaker. I don't see one buying a Mac just because they want to play video games, look at web sites, and type college papers. Granted you can do most of that on there, most users I've met don't buy Macs for that. I see them buy it to do music and multimedia. I see them buy it for personal preference and such. To me it's like deciding if you want to buy a normal power drill, or the industrial-strength one for special needs.
Fair enough. Setting aside the factor of respective strengths/weaknesses for applications, I would say that the main appeal that I've seen has been that OS X allows you to avoid the proverbial "Windows headaches".
We can debate the magnitude and significance of these headaches, but that's not really the point: the point is that no matter how insignificant they may be, there's always going to be some percentage of consumers who are simply fed up and thus, are going to jump ship.
My brother and his new iMac are probably a good example. The last Apple he owned was a //e ... circa 1984? So after 20+ years in the DOS/Windows camp, he's left. His son-in-law works in IT and had spent several nights at the house, trying to disinfect, update and protect his XP Machine....but in the end, he didn't want to lose any more photos of his first grandchild, so he jumped OS's and now has peace of mind.
To whatever degree you want to call this an "intangible" ... and I can agree that it is (since that's not the point) ... the point is that this consumer factor isn't something that neatly shows up on a simple price comparison, because it is the basis for product differentiation - - no so much as it is "For Apple" as much as it it is a "Not Microsoft"...at least initially.
Lord knows when any friend of mine buys a new computer, they're always asking why MS Word isn't on it.
Probably that's a product of the corporate 'Enterprise' environment. Historically, that was also where a lot of pirated software for home PCs also came from...which was also a factor in the growth of popularity for Windows.
EDIT: and FWIW, I can also recall hearing about office PCs that had their math co-processors stolen, RAM that had walked, hard drive upgrades, etc, etc. Depending on where you were, it wasn't always limited to just software.
-hh