Car, I'm assuming that the classes you're going to take are Intro courses, right? I have a feeling that the professors will probably let you in just as long as there are enough seats in the room. I'll echo Amy though...get there early...you don't know how many times I've had to sit on the floor on the first day!

On the first day, if the professor says "If you're not registered yet for this class, please don't take a syllabus just yet...save them for the ones who are registered..." I say just take one anyway.

Good luck!