Short of erupting into a Mel Gibson-esque racist rant, I can't imagine there's anything that you could do during the presentation that would be a turn-off to your crush. Unless he's a massive jerkface, he's not going to judge you for being nervous. We've all been there, and public speaking is particularly hard when you suffer from anxiety. I'm sure he'll understand and be supportive. Plus, it's just work. If it ends up being a total disaster, you can always laugh it off the next time you're talking to him. "Boy, that was a nightmare. I shouldn't have stayed out drinking until 2am last night. Want to hit McSwiggan's and help me drown my sorrows?"

As for the presentation: Have you tried picturing everyone naked? Just kidding. That doesn't really work. (Particularly if your crush is in the room. Too distracting.) Just like your first grade teacher said, P-R-A-C-T-I-C-E makes perfect. The more you practice, the easier it'll be once you get in front of your coworkers. Invite a few friends over, buy them pizza, and ask them to sit through your presentation and give you feedback. Say it out loud as much as you can. Perform it in front of a mirror, your cat, stuffed Snoopy doll, whatever works. Take a walk and run through it over and over again in your head. And remember-- no one wants you to fail. Take a deep breath, and show your crush just how awesome you are.