To be fair, I've done all kinds of multimedia work (audio, video, 3d, photoshop, illustrator, etc.) on both Macs and PCs, and the whole thing about Macs being better for that kind of stuff is just hype from the mid-90s that never died down, even when it became blatantly untrue.
First of all, for the same performance, a Mac costs more. Period.
Secondly, OSX can not multitask. As in, if you have two programs running, doing something that uses the CPU, unlike a PC with windows/linux/anything, the Mac won't just do both things slower; one of the two things will crash, if not the whole system. I've seen this first hand, and it's horribly frustrating. It's funny how Apple could take Unix, of all things, and make it so unstable.
Third, you have to pay extra to get a mouse with more than one button, let alone a roller (which is, in my opinion, the most useful addition to a peripheral since the advent of rudder controls on a joystick).
Fourth, it costs more, takes more effort, and is a horrible irritation to upgrade a Mac.
Fifth, Macs use a file system that makes retrieving lost (in other words, accidentally deleted) files impossible. If this hasn't ever been a problem for you, it will, some day.
Finally, because it's been bothing me quite a bit, Macs aren't nearly as stable as they're cracked up to be. On average, I've had the Macs I work on crash (as in 'have to restart') about once every two hours, while doing 'high'-end editing. On my home system (a PC running XP pro, of course), I think I've been forced to actually restart it once in the last month. Once!
So, think about that next time you say that Macs are better at multimedia. They aren't, and they haven't been since about 1996.
All that said, the Mac is still good at all the same things a PC is, except for getting games within the same year as they come out.
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Of course, all of that is IMHO and/or In My Experience. I'm just some kid who does photoshop and 3d work for fun, and has used both platforms quite a bit. If you don't believe me, at least make sure you've seen both sides of it like I have before making any blanket statements.
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Anyway, back to the point of the post, I'd have to say that you should get what you've used the most/like the most. It's all that really matters if you're doing word-processing, chat, surfing, and games that are most definately not cutting edge in terms of graphics. If you're most comfortable with a PC, get a PC. If you're most comfortable with a Mac, get a Mac.
Now, if you're equally familiar with both, and want the 'best' (or 'highest performance') computer for your money, then a PC would probably be better.