Don't do it! Put...down...the...PowerPoint!! If you've sat through an awful presentation, don't blame the tool, blame the presenter. It is time people started using PowerPoint for good and not for evil. Here is a blog article by Seth Godin on ReallyBadPowerPoint.
And please, do us all a favor, if you need to introduce a slide by saying..."You probably can't see this very well...." DON'T SHOW THE SLIDE!
AND Screen Beans suck.