hi, for high school next year, i'm required to have a laptop. i already know that i want a mac, but i just don't know which one. i will be using the laptop for most of my classes throughout the school day and for homework after school, so i don't want something that would be really small and hard to look at. (i know that i prefer larger screens over small ones) i dont really care about the portability. i am just wondering if $600 more is worth it for a bigger screen.
Assuming that your parents are purchasing this computer, and you are at a private institution (hence, the "requirement" for a computer), it sounds like cost is not necessarily a major factor.
You have not told us what you will be doing on the computer. Making another assumption, I assume you are just working on the Internet, writing papers, writing notes, and so forth. So, my recommendation would be to get the 13" Macbook Air and an external monitor for use at home. Unless your school supplies massive desks in each class (many institutions have chairs with those tiny fold up tables), then a big computer will be unwieldy. In addition, there isn't much point in having a huge screen to type lecture notes.
If my assumption is incorrect, and cost is a factor, why not just get a netbook with an external monitor? I know you said you wanted a mac, and I have one (13"/8g that I do my work on), so I can certainly appreciate the value, but there are other options out there for the kind of work you plan to do on it. Netbooks have plenty of power to do school work, they have far longer battery life (some as much as 14 hours), they are extremely light, and you can usually find excellent ones well under 500 dollars. If you spill a drink on it, have it stolen, or some other unfortunate accident, then it is no big deal. Over the course of your high school career, you could buy a new one every year and still spend less than you would on a 15" Macbook Pro. If you go this route, my recommendation would be Asus. I think they are the best manufacturer of these computers.
If cost is a factor, and you are dead set on mac, then I agree with the previous posters. Make sure to look at refurbished models. Or, you could get a used one. Over the next few weeks a lot of people will be trying to sell their Macbook Airs because there is supposed to be a model update soon.
Good luck in your classes!