Forgive my sarcasm but...
So..... if one has created a big presentation with all kinds of effects, graphs, etc, you
(not pointing to someone in particular here though) suggest people to do it all over again in Windows Movie Maker slide by slide, effect by effect??? (with the big chance that you can't even do the things you want, like using a graph from Excel etc)
Sorry but that doesn't make any sense at all...
Its like suggesting to rewrite that AppleWorks document letter by letter in MS Word while you could just convert it....
Using Windows Movie Maker (just because "it can burn to DVD directly") makes no sense at all because there are tons and tons of freewares and sharewares which can convert Powerpoint presentations directly to video without any sweat...
like: 'powerpoint, video' or 'powerpoint, dvd', etc
eg:
Free PowerPoint Video Converter,
PowerPoint to video,
Wondershare PPT2DVD, etc
Also note that a Powerpoint presentation is not a simple slideshow of pictures with a fixed resolution. Powerpoint saves pictures in a higher resolution than what you might see on your screen (provided the pics are in hires of course). This makes that the presentation will still be hires on another bigger resolution screen and not mangled up, stretched or blown up.
Use a dedicated converter if you want to create a decent DVD video out of a presentation. Don't attempt to recreate it in a video editing program (unless that program has a special option to import Powerpoint presentations of course).
Note: a presentation is not a plain old slideshow of your holiday pics; for that there are far better tools than Powerpoint...