If your dvd is not encrypted with one of the newer structural protection schemes, you can use DVDShrink to select individual titles to rip to the hard drive. Do this in ReAuthor mode. (click on DVDShrink in the previous sentence to get to the download here at cdfreaks).
The output will be a small dvd video that you can then run through Vob2Mpeg to get to mpeg files. It is still a two step process though.
To get divx from dvd you will need to convert the video. Mpeg4 is a file type and can use different video codecs, like divx, xvid and H264, none of which are used in dvd-video. DVD video is always mpeg2.
To convert to mpeg4 you can use conversion programs like Handbrake or Megui, or Xvid4PSP. Handbrake seems to be very popular for this.
Where do you plan on playing these files? Most older stand alone dvd players need dvd video, many newer ones can play divx or xvid in .avi container files. A few can use mpeg4 I believe. Blu ray players vary on what they can playback also, so you need to find out which formats are compatible with your particular player.
The smallest files at the same general level of quality will be encoded with H264 in .mp4 or .mkv files.