Did you even want to convert a PowerPoint presentation to DVD (using all free third-party software)? Unfortunately, there is no single free application that will accomplish this; however there are other options that you could take to achieve PowerPoint to DVD conversion using all free apps.
First, you'll need to convert your PowerPoint to a video format, in this case, AVI.
EM PowerPoint to Video Converter Free
The free version of this program will convert your PowerPoint presentation into a video file, and can output to a good variety of video formats (e.g. WMV, AVI, MPG; it can even output to BMP images).
The program works by “virtually” opening your presentation using PowerPoint, and recording the output to video. This program will let you specify (a) the size of the desired output video from a good number of options; (b) whether you want an auto transition between slides or the option to manually go through the presentation and record; and (c) if auto transition, how many seconds to display each slide. It will also let you specify an audio file to use with your video or if recording your presentation manually will also allow you to alternately record an audio/commentary track using a microphone (note: this function is actually available inside PowerPoint).
Experiment first to see if everything works out as you want it to. This program installs a media player and DVD burner in the program directory, and these cannot be uninstalled seperately. The DVD burner component, moreover, requires VOB or MPG files as inputs to author a DVD, so we won't be using this application.
Second, we'll burn the AVI to DVD
DVD Flick is a free DVD authoring program that can use videos from a wide variety of formats as input and burn DVDs that will run on any DVD player.
This program is extremely easy to use; all you have to do is add your converted videos (accepts many formats), title your project, and change any settings that you want (including picking a display template for the main menu, see below). Note that the program will use the names of the files you use as titles for the eventual videos on your DVD, so you might want to rename these appropriately before adding them to DVD Flick.