just gave you the best advice you will ever get on this subject. I have "helped" six people make the switch from Windows to Apple, not by telling them that Windows sucks, but by working patiently beside them on a Windows machine while I wore an Apple shirt. They try to start fights about it, but I don't take the bait. "Sure, Windows is a fine OS. They're both good, they both do what you need them to do. I just prefer the way it does this or that thing. Like what I'm doing here: at home on my iMac it would work like this..."
Eventually my boss got curious enough to check it out on his own. He did about a month of research and now we both have 15" PowerBooks. Never make them angry, just make them wonder what they're missing out on...