i've been using both Macs and PCs for over a decade in my line of work. They both have their benefits and drawbacks.
For 2D graphic applications and video editing, MAC is definitely more stable. It handles high level RAM usage very well (i used to have MAC machines with 16gigs of ram, and this was back in 2003). Video editing was so smooth with real-time preview in After-effects and Premier. And MACs definitely have a smooth interface. It makes working feel "slick." Plus their designs make the office look clean and high-tech (love their G5 and Cinema screen designs). Downside...about 1/3 higher priced than comparable PCs, and their UI is sometimes too friendly...hiding certain features.
PCs on the other hand, is great for 3D applications and games. There's a company called BOXX (which is the best, imo, for high-end workstations), and man, their PCs are FAST when it comes to MAX/Maya, etc. The high-end video cards made for PCs are also extremely powerful. Try running FSX on a FireGL v8650 2Gig and watch the CRAZY fps....but again, it's a 3,000$ video card! Downside, usually ugly designs that doesn't look good in a design studio, and sometimes buggy software (tho a cleanly installed PC that's well managed is also very stable). And yeah, Vista...umm....lets not go there. All my PC machines are running XP pro.
I'm not a PC nor a MAC fan. I use each to get my work done. I think both sides are making great advanced towards making our work and life easier.
What i actually want is a powerful, small and wireless PC that i can put into my pocket. I guess something like a iPhone, except it has a G5 built inside. And when i get home, i just put it on the table, and it auto-connects to a wireless monitor, and i start working. I think something like this is very possible in 10 years. Very similar in concept from a casset player in the 80s, to the micro-iPods of today.
-feng