As long as the other person is someone who shares common interests with me, I can talk to any sex equally. I'm not nervous around girls, really, but I talk more to boys, since they are the ones who have the similar interests, though I do have a couple of friends that are girls.
Not many girls at our school are into what my group is into, and that's debating, video games, and the internet. Basically, we're the nerds. XD