I have been ripping my DVDs to MP4's just so that I don't lose any of my DVD's. I find that Handbrake works really well, there may be some problems if the Discs are copy guarded, I have found that the decryption softward put out by Sly Soft, is really good. Those are what I use and I only occasionally have issues, but these products don't leave a water mark. Hope that helps. :-)
Sonya