If you wanted to play with "just the movie" part of a disc, grab dvdshrink (it is free) and open it up and then click on 'Open Disc'
Then once it has analysed the disc for you, click on 'reauthor' and then just grab 'title1' from under the heading 'main movie' and drag it over to the dvdstructure window on the left hand side.
Under the 'compression' tab - choose "no compression"
Then choose 'Backup' and under 'Select Backup Target' choose "hard disc folder"
Then off you go.
(You could also untick the option under 'Edit/Preferences/Output Files/ Split into 1GB chunks if you just wanted the whole movie in a single file)
Once that is done, grab virtualdubmod (it is also free) and you can open the new .vob file(s) from your hard disc directly.
You can then save it out into any format you want, or do what you like from that point onwards with the video editing software of choice.