I would say for the same processor, ram,  speed etc nowadays they’re pretty much on an even par. Sure you can buy cheaper PC’s that do the job fine, but you don’t get the bells and whistles or the metal case, not to forget the irritating Mac mouse that has a mind of it’s own and the batteries only last 2 minutes before you have to change them again. But in this economic climate, people aren’t so worried about the pretty stuff and don’t mind a bit of plastic as long as it does the job it’s meant to do.

In my industry, graphic designers tend to go for the Mac while the devs go for the PC. Our office actually has a couple of devs who swear blind by the Mac, while me, designer/developer, wouldn’t want to work with anything less than a PC.