As a lecturer, i gave a lot of presentations on each of my class and i use LibreOffice (previously OpenOffice.org) as the main tool to deliver the material. I often prepared the material long before the class, but sometimes i prepared it one day before the class started.
In every slide i made, i tried to make it as simple as possible, but still gave the complete information to the audience, since i know that the audience http://www.blogger.com/img/blank.gifdoesnhttp://www.blogger.com/img/blank.gif't like too much garbage text in it. They prefer more images on it because a word can visualize a lot of things.
Tonight, i just realize that my method is not 100% correct as there are a lot of improvements i can use after i read Presentation Zen Design: Simple Design Principles and Techniques to Enhance Your Presentations and slide:ology : The Art and Science of Creating Great Presentations.
If you often give talks to other people, i would recommend that you read both of these books. It's worthed and it might give you a lot of inspiration when creating your next presentations.