In the previous post on business computing, I wrote that I didn't want a PowerPoint clone at all.
I've taken many courses where PowerPoint was used by professors and it was horrible. The amount of information on each slide is too low. It doesn't matter how much text there is, there will always be too little information on it. The worst was a database class I took at college. The instructor had all the important information on slides. It took more than 5 slides to say to what could have been said in a single paragraph. It's next to impossible to learn from slides like that. There's no room for examples, no room for comments, etc.
I think the reason PowerPoint is used by professors is because of the sales, marketing and business types that invaded university campuses. As someone said (can't remember who), PowerPoint is the tool of the salesperson. It lets you instill a sort of tunnel-vision in your audience.
The best lectures have been given without the crutches of PowerPoint or overhead projectors, and many of them were written down and published in book form. I have a book of Noam Chomsky lectures on linguistics and there is a lot of information in it. I'm amazed that people sat through long lectures like that.
Avoid PowerPoint if you can. If you must have slides, only put headings or a few brief points on each slide. If you're going to distribute the slides afterwards, also try and have a speech or notes for your speech prepared. Basically, pretend you're giving a grand old lecture in a grand old lecture hall in a historically significant university.