I don't know how relevant it is for what you're looking for, but macs don't have the bottlenecks that PC's have when it comes to processing graphics. The Mac hardware is designed to work with higher resolutions/bit-rate graphics - very helpful if you're doing any work with video's, or doing any kind of graphic manipulation.
There's also the color. I don't know what it is, but I've never worked on a PC that was as color accurate, or as vivid as the Mac's I've worked on.
Plus, having a Mac just makes you cooler.
