Try
http://www.videohelp.com. They have a linux forum about this. I was able to follow their Windows tutorial on how-to rip DVDs with DVD Decrypter and DVD Shrink and then create ISO files so that my Linux system can burn it using cdrecord-PowerDVD to record to DVD-R. If you're using DVD+R/W discs you'll need the dvd+rw tools (specifically growisofs). Using my Windows box to rip was much easier than finding something for my Linux box. Especially since I run Linux in command prompt only. Also, I learned the type of media that you use is very important especially if you're intending to watch the DVD backups on PS2 or Xbox systems. Good luck.