I've come to beleive that the people who trot out the same ol' tired arguments about language X (where X is Perl in this case) aren't going to be convinced otherwise.

I just start asking them questions about what they are using, and people usually fall into the geek trap: they love to complain about things. Have a few questions in your quiver to help that along, but play somewhat dumb instead of confrontational: "What's that Santy virus thing?", "Speed isn't a problem?", "You must have some big hardware for that amount of traffic.", and so on. Pretty soon they're bitching about their stuff instead of yours. When you part ways, mention that you're going to the movies and ask them if they have time for it. If not, tell them that's the difference between Perl and their stuff. :)