I have done several shows with Keynote. I have also done several tests upconverting SD DVCPro50 clips to play in a 1024 x 768 presentation.
All still graphics for the slides are built at 1024 x 768. All videos are 720 x 480 DVCPro50.
So far all the videos I have tried to up rez to 1024 x 768 or 800 x 600 using compressor, AfterEffects, Nattress right in FCP etc, don't look as good as simply opening the DVCPro50 clips in QT player and going into the properties and making sure that high quality and deinterlace are both checked. These look better than any of the other methods.
I scale the clip in Keynote to fill the screen.
Anyone else take the DVI out of a MacbookPro laptop straight to the projector and use SD video clips in a 1024 x 768 presentation and have another workflow?