Of course this request is a topic where there is much controversy. Myself, I agree with your usage request: making a backup of a DVD you own. With that said...
There are many such programs doing what you desire. I find though that 'AnyDVD' and 'CloneDVD' are the best for the Windows platform.
A 'free' way is with 'DVD-Decrypter', and its output will probably work with Nero.
Is there any way to copy a copyright DVD? I have no intentions of selling, distributing, profiting etc. I simply want to copy my DVD's, as I do with all my CD's, for travel purposes. If I go on vacation or bring a DVD to friends house, I don't have to worry about it being mishandled, scratched or forgotten because it's a copy and I still hold the original. Is there any way to do this? I have windows XP pro, sony dual layer dvd burner, and Nero 6.