Hmmm... well, first, you have to decide.... do you want a self-playing movie, or do you want something you can control the speed of?
If you want a self-playing movie, I believe PowerPoint can export to QuickTime. Export it to a high quality quicktime file, and then just drop it into iDVD.
If you want something you can control using the arrow buttons on the remote (so you can talk or whatever, and then change the slide when you're ready), you need to make each separate slide it's own picture file, then use iDVD to make a picture slideshow.
Hopefully this is a good overview. Whatcha have in mind?