To compress DVD movies (which occupy around 9 gigas, as you all know) and be able to record them on a DVD-R (4.7 gigas), there's nothing easier than DVD95Copy Pro.
DVD95Copy Pro also lets you select the elements to record, to save even more space and remove the things you don't want (menus, languages, etc).
This is of vital importance when trying to get the best quality in the resulting video, as the more data included the more to compress, and so the worse the final quality of the movie. DVD95Copy Pro always tries to give top priority to the movie before the extras.