Can you get a girlfriend if you're a nerd?

Yes. First of all, there are nerd girls too. Second, "nerd" is not a personality trait but rather a kind of behavior. Love is based on personality however, and behavior is comparably easy to change.

It's true however that as a nerd you will tend to have less chances of finding a girlfriend simply because you have less contact with girls.

Of course! Define nerd anyways. most people call really smart people nerds so... well i wish you luck

Sure. There are many nerd girls out there, and if you aren't confident around girls in real life, then you may want to visit the site "Nerdfighter", where lots of people (girls included) who call themselves nerds talk.