Almost all of my co-workers use PCs, because that's still the only thing the company will buy for them. (I use my own MacBook at work.)
A number of my co-workers are intrigued by Macs and Mac OS X, and since the switch to Intel I've had the opportunity to show off how you can run Windows, Linux and Mac OS X on a Mac (i.e. with Parallels).
No one's ever made fun of me or, you know, questioned my manhood for using a Mac. The main objection I hear, still, is that Macs are too expensive. And I think that's a fair objection, although the prices have been coming down over the last few years.