If you care about iPods and want a new one for free, wait for the back to school special.
It sounds like a MacBook is what you're looking for. I personally prefer the iMac, and just bought one, but that's because I do a little bit of heavy video editing (HD video). MacBook couldn't cut it for me anymore (it just isn't designed to).
MacBook Pro is overkill for you for sure, but the iMac gives that added boost in power that will make it last longer into the future than a MacBook will. If you will basically leave the item stationary in one place, an iMac is a good idea.
Just one piece of advice. Get some knowledge about the situation with your dorm/apartment. Are break-ins frequent? Will your roommates leave the door unlocked, or get drunk and not realize that three dudes are walking out with your iMac?
I recommend laser engraving of your name and a more permanent address on the back of the machine, and also make sure that you lock it down using the security lock. Try to find a good lock that isn't some cheapie thing, and then run the thing inbetween or around some pipes in your dorm (something secure, not just around a table that can be lifted up then the cord slid under). It might even be worth looking into two different security systems together, such as the basic security lock + some other device or setup. Definitely make sure your name is on your system, though consider that it might make it difficult to sell in the future if that's a possibility for you.
Additionally, make sure it's placed in a good spot. If you put it in a general community-use spot in your dorm room (such as the "living room" or whatnot), when your roommates party, it could get scratched or knocked over. I let my roommates use my computer when I set it in the community space (my PC), and my mouse was never the same. No one fessed up to it, but they broke my $75 trackball mouse's right click button. It died completely less than a few years later, I believe due to complications from that first injury that were never properly healed. ... I still mourn the day, and I will never forget my faithful trackball mouse.
