Make sure you use the TIFF option. All other options compress the image.
Also, if this is for air, or at least going to be played over a standard def TV set, make sure all the essential text is in title safe. Also, make sure the colors are all broadcast safe. If the whites are too white, the audio will buzz.
And make sure all the type is readable on screen. Some presenters cram a bunch of info onto each slide. If you have the powerpoint file, break down some of the more dense material into multiple slides. Only one or two ideas per slide.