How to make a fanboy less fanboyish?

So I have a good friend, who is a "militant" apple fanboy. He somehow dislikes and bashes all non-apple products. Even though I agree with him (basically all the time :) ) but I know that people have different preferences and needs. there's absolutely no reason to bash the "other side" for having other opinions. I find it very annoying, like many of my friends. So how do I stop him without being rude?