I've decided to get a bike to ride to and from class starting this fall. The trip is about a mile each way. I just have no clue what type of bike to buy. I've got very little experience riding bikes. Haven't done it in a very long time. I'm a typical college student, not in shape, but I think I can handle the ride. I've got a few options in mind, and would enjoy some feedback.

I've heard that an old mountain bike with a rigid fork can make a decent commuter if you put slick tires on it. Is this true? I found a Motiv Rockpoint in a local pawn shop, and was considering buying it. It didn't have any suspension, but that's about all I know about it.

Would I be better off with a used road bike? I've never ridden a road bike before, and honestly it looks uncomfortable. I've read hybrid bikes are a good compromise, but I can't find any used ones, and new ones are too expensive.

My budget is pretty tight. $300 max, ideally. Any ideas?