Now that they're price-competitive, the only reason to use a PC over a Mac is if you have specific, PC-only software that you need to run.
I use both, and prefer the Mac by a large margin. Very easy to set up and use, not nearly as vulnerable to viruses, almost never get annoying pop-ups, etc. And you NEVER have to reboot.
I do heavy photo and video editing as a hobby, and there's no better platform than Macs for that. I'm an attorney by profession, and use Microsoft Office for the Mac; I never have a problem with document compatibility with other lawfirms, unless they're using WordPerfect (which I can use, it's just not as easy since I have to run it in Mac's old operating system, now called "Classic"). (If necessary, you can buy a program that will allow you to run Windows, and alll PC programs, on your Mac, as well.)
Apple has a new Mac Mini that's very affordable ($499), if you already have a good monitor and keyboard. But you can't beat the iMac for overall value. For $2k, you can get the 20" widescreen model, which is what I use -- you won't regret it! If you have an Apple Store near you, or a Comp USA, go check them out. If you're a student or teacher, you can get a nice education discount, as well.