Making presentations is a part -- or should be -- of most business analyst's work. This involves selling your ideas for the new system, trying to get a consensus on what the scope of the problem really is, and generally convincing people that you know what you are doing. And let's be honest, you are not going to be successful with a dull-as-ditchwater PowerPoint presentation full of bullet points.
Please read Garr Reynolds' book, and take just some of how advice. Your audience will love you for it, and who knows, they might even listen.