Macs aren't any better for graphic design, editing or music. Photoshop runs better on PCs, FCP is almost the same as Premiere Pro, and Logic, Live, Reason, and every other music program are for PC AND Mac.
Its just your personal preference, one isn't inherently better (OS excepted).
Everyone going around saying how much better Macs are for "art" are just evidence of how killer of a marketing department apple has. I'm not biased, I have a Macbook Pro and think its amazing. I have done more photoshop and illustrator use, music production, and editing than a lot of people have, on both systems, and this is just my opinion on the matter.