As far as actually getting up and talking, all I can really say is that you should stay relaxed. Those people want to like you. They have chosen to come and listen to you because they know you have something interesting and exciting to tell them and they want to know more.
The best talks are the ones where the speaker is relaxed, confident, and speaks as if to a small group. You already have that experience so you know the sort of it's-just-the-5-us-us-here-talking feeling to aim for.
In terms of your slides. Remember that anytime the audience has to read a slide or make sense of a chart, they are not listening to you. It follows then that you should not have much text (if any) on your slides.
Your slides should only contain simple images supporting whatever point you wish to make during that part of the talk; simple charts (2D, no bling); or words written in a minimum of 60pt (sans serif font)
When testing them. Put them up on your laptop and look at them from 30 feet away. If you can't make out the detail, then neither will your audience during the real presentation.
Any real detail, data, background info, etc should be in a separate slide deck that you hand out or make available to download.
One book you might find interesting (I know I sure did) is Presentation Zen by Garr Reynolds [1].
Best of luck to you. I hope you have a great time
[1] http://www.amazon.com/gp/product/0321525655/103-6148611-3957...
- Don't Make Me Think by Krug: http://www.amazon.com/Dont-Make-Me-Think-Usability/dp/032134...
- Apartment Therapy by Gillingham-Ryan http://www.amazon.com/Apartment-Therapy-Eight-Step-Home-Cure...
- Presentation Zen by Gar http://www.amazon.com/Presentation-Zen-Simple-Design-Deliver...
- Belisarius Saga by Flint and Drake http://baencd.thefifthimperium.com/13-TheBalticWarCD/TheBalt...
- Wise Man's Fear by Rothfuss http://www.amazon.com/Wise-Mans-Fear-Kingkiller-Chronicles/d...
- Wizard of Oz by Baum http://www.amazon.com/Wizard-Oz-Puffin-Classics/dp/014132102...