DVDdecrypter and DVDShrink has been my favorite choice. It has served me pretty well all along. Sometimes I have used DVDremake also...
Undoubtedly, I recommend backing up your personal DVDs. In the good old days of VCDs - I have lost atleast a couple of dozen videos - just because I assumed that CDs were longer lasting. (what a misnomer!!)
anyways, now I use this HDD-based Media Center
- and cant be happier... its just fun watching movies on a 56" widescreen... and it works almost like 300-DVD disk changer !!! :)