You have two weeks. Rehearse the shit out of your talk. Run through it several times every day. Do it until you're completely sick and tired of hearing yourself, and then run through it some more. Get friends and family to watch. Videotape yourself. But go through it as much as possible. That's the most reliable way to beat the nervousness and deliver a kick-ass talk. I know Steve Jobs makes it seem like it's something you have or you don't, but I've read he spends like 20 - 30 hours prepping and rehearsing for his keynote talks. There's a word for this: sprezzatura. Good luck!
http://lifehacker.com/5449141/deliver-polished-presentations...