It is noticible at idle, and goes up in pitch the faster the car is moving (RPM's actually). I open the hood and listen, but can't identify where in the bay it's coming from.
If it's just the belt that's causing the squeaking, either you could replace it or save a few bucks and just put a little tooth paste on it. Laugh if you want, but tooth paste actually gets rid of the noise. That is, if it is the belt causing it.