The best software to make a perfect backup of a dvd is DVD-Backup for Mac OS X.
The superdrive can only burn to DVD-5…that means DVD which can support (only) 4,3Go (4,7Gb). Most DVDs are more than 4,3Go so they will require some reencoding in a lesser quality to fit on a 4,3 Go dvd. This is called the DVD-9 to DVD-5 technique.
There are a few softwares that can do this:
ffmpegX (the most complete application, but a little difficult to use at first)
For a practical guide doing DVD-9 to DVD-5 check here:
For more information for DVD on the mac check the following forums:
Hope this helps and welcome to the mac/unix plateform !