A Mac In An Enterprise: This is a good article detailing the travails of one guy trying to use a Mac in a PC-based IT shop. He manages to do okay in the end.
“For the last two years, I have had to use a Dell laptop at work running Windows 2000 in a mid size company with 300-400 employees. After suffering through several complete rebuilds, blue screens, as well as dealing with patches and security upgrades, I decided that enough is enough.”
More and more, I’m shying away from monolothic infrastructure systems like Exchange precisely for this reason. If you stick with client-based apps, like SMTP email, then end users can run what they like. Make each client as self-contained as possible.