As I've had similar question and found a solution finally, I'd like to share my experience with you.
At begin what I thought is to convert PowerPoint file to video and then burn the video file to DVD. I've tried some PowerPoint to video tools and found that they can't generate DVD Menus when I burn ppt to dvd.
After that, I searched Google and found some tools which can burn PowerPoint presentations to DVD with DVD Menus. And what I am using currently is Acoolsoft PPT2DVD
What I suggest is to go to download the free trial software from below link.
http://www.ppt-to-video.com/powerpoint-to-dvd- overview.html