Depending on your major and your interests, you will need a certain kind of computer. An art, graphic design or film major will need a computer with tons of memory. Something like an Apple Macbook Pro or a Sony VAIO. These computers have massive amounts of memory and speedy, powerful processors. If you don't intend on doing much studying in college and would rather play online video games, these computers would probably be a good match for you as well, though I'm sure that's not what your mom intended it for.
If you are looking for something a little lower on the laptop price range and don't intend on shooting down aliens on the Internet, a more mainstream option should suit you quite well. Something like a Dell Inspiron 14R should provide you with the specifications you need like a long-lasting battery for those four hour lectures, document software and a built in web camera for calling your parents when you need money.