Speaking in public is something a lot of people have trouble wtih. You may have to give a presentation at your local VMUG or even give a presentation to your IT Director. So how do we learn how to speak in public? Well...practice, practice, practice.
Power points are a somewhat enablement tool for giving presentations, though they can be somewhat boring if the speaker doesn't do a good job. So, know your power points and give your listeners something new that they don't see on the slides...don't just read off them. If you're in IT, white boarding is often preferred, if you're talking to other tech folks. This means going to the marker board and talking through designs. Really mapping things out and answering questions through white boarding.
If you're nervous to speak in public, check out Toast Masters. They've been around for ever and they will help you get over your nervousness and correct bad habits. I highly recommend checking a club like this out. They're usually available in your geographic area.