This has got to be one of the touchiest subjects in all of computing. But I'll try to explain the real world differences and some points with as little bias as possible. First, it is simply down to user preference and budget. Macs cost more for the exact same thing, plain and simple. That is not some sort of slander to Apple or Apple users, that is just simply a fact. There is also nothing in the end result of your work that you can achieve on a Mac that couldn't be done on a PC for 1/2 to 1/3rd of the price. And with only a few exceptions the software you use to edit your work are identical on both systems. So it's almost entirely an operating system environment/preference that you are paying the difference for. If you cannot stand Windows/just have to have an OSX OS, well then there are almost no two ways about it (at least not legally) you have to get a Mac.
Macintosh computers run on the exact same hardware as Windows and Linux PC's. The difference is that the OSX operating system will only legally install on machines that are built by Apple. Windows and Linux operating systems can be installed on any compatible hardware, including machines built by Apple. This style of software (e.g. OSX) is known as proprietary software. Proprietary allows Apple to release only a small handful of system configurations to the market over the years and then only ever have to worry about keeping compatibility between system configurations working smoothly across these small handful of few variations. This gives the perception that Macs just run great, which is often but not always true.
Windows on the other hand (as well as Linux) support a near infinite combination of system components, developed and configured by a myriad of developers and re-sellers. If you know what you are doing yourself, or choose your manufacturer/seller carefully, then a Windows machine can be just as stable and smooth as any Mac, and if you shop properly, it can cost less than 2/3rds to 1/2 that of a Mac desktop or laptop. That's how extreme the price markup is, for the exact same (or often even more powerful) hardware.
This is not to say that there aren't plenty of PC re-sellers that charge very high prices, equal to or worse than Apple for the exact same underlying components. There are plenty who do. The difference is that on the Apple side of things, there are no alternatives, only Apple. On the PC side of things, there are an infinite number of alternatives.
So if cost is an issue and or having OSX as your OS is no virtual requirement for you, then the way to go is a well built PC from a reputable re-seller who's retail markup is not nearly as absurd as the rest, and there are plenty to chose from, otherwise, you have only one choice and it's a take it or leave it decision.
These guys sell desktops as well, but take a quick look at their laptop offerings, and compare them quickly to Mac Book Pro's, http://www.ibuypower.com/IbpPages/Notebook.aspx
The price differences are staggering, on average the systems are 1/2 the price for an equivalently or more powerful machine. And these devices are fairly well regarded among PC users, I'd take one in a heartbeat. They sell desktop machines as well at reasonable prices however for desktops, I always build my own piece by piece from various online retailers. The difference between a desktop and a Mac Pro desktop is quite often 2/3rds the price and often you get more powerful equipment as well on top of a 2/3rds price discount when going for a PC.