M$? Grow up.
To answer your question,Yes. I use windows XP at work. We also have server2003. Exchange is awesome. Roaming profiles is awesome. I never thought that I would say that.
I haven't had any problems with it so far. We have knowledgeable techs maintaining our machines. I'd prefer to use a Mac, but if I can get my work done on Windows, then who cares. I'll use my macs when I get home.