Be it two or two hundred people, you should be delivering your lines in the same way. That is, don't get nervous, focus on the task at hand and get the job done. Understand that those in the audience know it is not that easy to speak in public and they want to see you do well. Use this positive energy and give a beautiful performance. We are often most nervous when we must do something that we have not mastered.
Few people are master public speakers, but most can do well if they prepare properly.
The key to preparation is knowing your topic inside out. If you are an executive at Coca-Cola giving a speech on the competition, you'd better know every nook and cranny about your company, as well as all the other soft drink companies. Take the time to make notes and summarize your ideas into small bites of information. All you need to do afterwards is remember the information bites and expand on them during your speech. If there is a question and answer period, try to anticipate possible questions and prepare answers in advance.