Pretty much the same as Ivo and Hydro, I have to do a fair number of presentations and lessons, with a number of different tools available.
When I first started teaching I had nothing but handouts or maps, and a board with markers, then graduated to powerpoint, then back to slides on an overhead. But I can present or teach with or without any of these.
When i do use powerpoint, it depends on what I'm doing, if I'm doing a presentation to a prospective employer, I put more on it than I would if I where teaching. Because it gives them somethign pretty to look at other than my face. Where as when I'm teaching, the're a tool to display key points or workings, the same as what I would write up in chalk. And they should be paying attention to me, not the handouts, and not the powerpoint, but me. So I give detailed notes around key points, and illustrate some of these on the overheads, but they are expected to take their own enhancements to the notes. Where as employers I need to lay it on, because I'd be presenting to customers or contractors, and they like a little bit more. But never go up to the level of Death by Powerpoint by using it as a script. I never script presentations or lectures, it doesn't work.