"but I would prefer the mpeg1or2 due to the smaller file size."
Well, you're in for some problems then, Powerpoint doesn't like to play nice with MPEG Files. We have had MANY clients bring us their PPT presentations and they can't get the video to play. We re-render the video to a AVI and all the problems are gone.
The Cinepak codec should be there. You'll need to create a custom AVI template to use it, it is available in the Video Format dropdown on the Video page.
If you want the ppt file to play on a Mac as well as Windows then MPEG1 is your answer.
To the best of my knowledge PPT will play nice with mpeg1 but not play mpeg2 at all.
However, when you install the Mainconcept encoder it flumoxes powerpoint. There is are files to rename that fixes the problem. You might search for posts by sonicepm or sonyepm or maybe even by me. somewhere is a note about this.