I've given lots of talks that included visuals. I understand visuals. But I also know that visuals are overpowering things and when you include them, they turn your listeners into viewers. That's okay, if your verbal content is powerful enough, but a weak verbal presentation overmatched by visuals is like a boat with too big a sail: you will run yourself under the waves and sink.
But, you know -- if your verbal content is powerful enough, then you probably don't need to add visuals; in fact, visuals would restrict the applicability of what you say to a single channel, whereas words can paint more possibilities in people's minds than pictures can. Which is just another way of saying that if you're a good enough preacher, you don't need pictures.
I've seen so many mediocre power-point presentations, sat through so many Emmaus talks where the posters had little to do with what was being said, even seen sermons that became about the pictures. And don't get me started on spelling: one of the worst power-points I've ever sat through was given by a representative of the General Commission on United Methodist Men, in which a major spelling or grammatical mistake occurred on at least two out of every three of an interminable number of slides. It was like a reading of Vogon poetry.
Here's an idea. If you really must be so rarified or technical that you fear that people will have trouble following your very important points, the best technique I know is simply cut it short. A shorter sermon, more tightly focussed, will always be more powerful than a longer sermon, however groovy the pictures are.