Then the MacBook Pro with 13" display and C2D CPU will suffice, but you may like the bigger screen of the 15".
But spec wise, the C2D is more than capable of doing what you want to do, now and in four years.
Now you have to decide, if you want Mac OS X or Windows primarily.
I agree with you. For the OP's needs, I would seriously consider the 15" MBP.
I think either would last four years as long as you take really good care of it. The tech in either is fine. A C2D 13" with 320m is plenty of computer except for future gaming. The Core i5 15" is even more computer but does have disappointing graphics in my opinion (yes better than 13" with 320m but 330 GT is disappointing compared to PCs).
If I were you OP, and money were not an issue, and you really want an amazing laptop that will last you four years, consider a Sony Vaio Z. It is the weight of the MBA. It is more powerful than an MBP. Windows 7 is truly great now, and that Z has more upgrade options for a more future proof PC for four years of college.
There are a lot of nice computers that are much better specd than the 13" MBP or 15" MBP at a lot lower price. However, you aren't going to get as great of build materials or design. Most importantly, only a Mac can run OS X AND Windows 7. I would find it a great advantage to have access to both OSes. It really comes down to ALL of the variables... mostly what you want, what you need, and how much money you have to acquire the best for the four years you'll need it. Any current MBP, even a 13" MB, would be really nice for your needs.
In terms of durability, I find the 13" MB to be the most durable Mac. The aluminum sure is pretty but it damages far too easily. If you're certain you're not going to damage it, then go for the MBPs, but understand the difference. Also understand that a 13" MB is $849 refurbished or $899 education pricing.
You can also consider the 13" refurbished MBPs. Last week they had them for $929 which is a $270 price break over new... but again education pricing is $100 less new for the MBP. Just be sure you get the best value for you. Also consider if your parents have a credit card with extra protection or that doubles the warranty.
Good luck.