same goes for filling the disc with moving menus and trailers etc. my menus are under 35mb, that's 7 images, 7 looping audio tracks for them, + the main film and movie audio.
maximum space for movie image, then a 2.0 dolby stereo Ac3 file made from the PCM recording.
If you're going dual layer then yeah, PCM is great to have, I just think it's a waste of time on a DVD5 that's all. there are better things to use you disk space on.