Frisco, I've been thinking about this speech you're going to give, and I have a few additional pointers.
Don't allow your argument to get bogged down in issues of ideology, especially when it comes to religion. Unless you're an expert on world religions, don't get into a "West vs. Islam" argument. It will be no-win for you, and it irrelevant in a discussion about what is in the U.S.'s security interests in Afghanistan.
Don't allow anyone to try to use morally equivalent arguments. What I mean by that is, don't let anyone get away with "that's OK, because..." for example, "well, Muslims are only reacting to the West's provocations," "yes the Koran says 'kill the infidels' numerous times, but the Bible has some bad stuff in it too," that kind of stuff. It's usually a distraction from the point at hand, and again is usually irrelevant to the underlaying discussion.
Make sure you don't ever apologize for your country's actions. The United States of America is the foremost force for good in the entire planet- that's one of many reasons people hate us. We're not perfect, but no country is better.
When you have a chance, get a copy of a book called "The Politically Incorrect Guide to Islam and the Crusades." You'll probably have to order it online because I doubt your school library will carry it. It is full of information you may find interesting. I read it on my first deployment to Afghanistan and it really opened my eyes.
Finally, when you're considering whether or not the U.S. should stay in Afghanistan, make the case that the U.S. doesn't want to stay in Afghanistan, but we need to do so as long as organizations like Al Qaeda remain an existential threat to the U.S. Once that happens, we can leave. The Taliban was in power in Afghanistan for years before we went in; it wasn't until the TB allowed AQ to use Afghanistan as a base to launch attacks against the U.S. homeland that we got involved on the ground over there. If/when Islamic militants cease to be a threat to both the U.S. and Pakistan (mainly because PAK has nukes), then the U.S. will quite happily leave Afghanistan.
And for your own education, look up the Haqqani Network.