I know just what you mean. I bring my iBook with me to each class and use it if I need to. Why?
Logging in on a school PC takes two minutes. Plugging my iBook into a jack gives me full access in under 10 seconds.
Anyhow, I whipped it out to work on something in my "Operating Systems" class, in which we were learning Unix. The guy next to me, who used to be an NT administrator and has never used Linux, Unix or Mac in his life immediately began slamming me.
My tutor, a young woman who is a bit of a Linux evangelist, immediately took an interest and said: "Hey, a Mac. Are they any good?"
"Oh, yeah." I said "The whole system is based on BSD Unix."
"Say WHAT?!" She said.
I showed her the terminal, the config files, and the way System preferences can start and stop Apache and FTP servers with a single click.
"I can run all the Unix servers and development tools in the same environment as Photoshop and Office." I told her.
So, clearly some people are willing to say "I own a windows machine because they are the best and anyone who says otherwise is a damn fool." while other people are willing to consider that other systems have their virtues as well, and that maybe the world doesn't revolve around windows. Some people never stop learning, and others never stop thinking they know everything already.
My Java teacher told me a Mac would be useless, as we would be starting with the BlueJ development environment for windows. I showed him BlueJ for OS X, and a number of projects I had compiled that ran perfectly, and he never mentioned it again. I mean, isn't Java meant to be multi-platform? What the hell are they teaching these kids?