I know you're using PowerPoint, but have you thought about trying Keynote? I work on both Mac and PC platforms, so I use usually use PowerPoint for presentations, but for stuff I want to put in a movie I use Keynote. The advantage of Keynote in this regard is that you can take a presentation and then use the Export feature to save the presentation in a number of different formats, including PDF and JPEG. If you choose JPEG, Keynote automatically creates a separate image for each slide in the presentation.
I just used this approach yesterday. I imported a couple of slides into Keynote from PowerPoint (opened the PP file in Keynote), then I used the Export feature to save them as individual JPEGS on my desktop. Finally, I imported them into FC.
I paid $79 to upgrade the trial version of iWorks that came with my latest Mac to a fully licensed version, and while I don't have any real use for Pages, there are a lot of things I like about Keynote compared to PowerPoint. The Export feature is one of them.