Powerpoint is a tool. In the hands of most it’s a blunt instrument yielding bloody results. In the hands of the artisan it’s an orchestral fireworks display.
There are a couple of paths to improving your presentations. First, hire the design team that Al Gore used in creating An Inconvenient Truth. Second, read Presentation Zen and study the styles of Godin, Lessig, Kawasaki and Takahashi. Using images is important no matter what style you use so read this post about where to find good ones. (Thanks to Michelle Golden for sending the aforementioned information).