I've been experimenting with giving presentations without slides for a while now. I did so again today. Coincidentally, today I also visited the AYE Wiki, WhyWeDoNotUsePowerPoint.
People always seem a bit confused when you don't hook up your laptop for a slide show. They look at you like you came unprepared. Don't fret it much; if you are prepared it will be clear by the end of the presentation.
It's worth questioning your motives in using PowerPoint slides. After all, the three most practiced types of public speakers almost never use slides: Politicians, preachers and teachers. I try to learn by watching them.
Slides do have value. They certainly make excellent handouts to take notes on. They appeal to the visual learners in your audience, augmenting your spoken word. They can also be an effective way to show detailed information like charts or even pictures, although, you could just hold up a large chart or picture. That's what politicians do.
On the other hand, you shouldn't use slides as a script or a memory aid. People get bored watching your read a slide set. Nor should you use them as proof that you have properly prepared. Everyone will know if you prepared by your content and delivery. Finally, you shouldn't use them as an aid to soothing stage-fright. It's much more effective to prepare better. Use a podium instead if you must (but that's another posting).
I find when I present without slides I get a much better connection with the audience. I can tell what's working and adjust as needed. It helps me to focus on the goals of my presentation, and tailor the delivery to meet those goals rather than fit the confines of PowerPoint. People seem to like it.
While it's not for every presentation, I'd challenge you to give it a try.