I use DVD Shrink to do the decriptions. All that stuff can be very complicated. I also use Nero to do the burning, but you need to decript DVDs before you can make copies, so Nero alone won't do the trick.

Most DVDs are designed to prevent you from making copies.

The first preventative measure is encryption. Commercial DVD titles are often encrypted, which prevents you from either copying them to your hard drive, or if you manage to do so, being able to play the resulting files. DVD Shrink overcomes this problem with built-in decryption algorithms, which means you can use DVD Shrink to backup a DVD directly, without requiring any other software.

The next problem is not so easy. Most DVD video titles are simply too large to fit, without modification, onto a single recordable DVD-R disk. DVD Shrink overcomes this problem by compressing or "shrinking" the data from your original DVD. The latest DVD Shrink 3.2 contains state-of-the-art compression algorithms, rivalling those found in the best commercial softwares.

DVD Shrink also allows you to re-author your DVD. You can make your own compilation from one or more source DVDs, or select only the parts of a DVD which you intend to view, thus preserving more space on your backup for the highest quality viewing.

Get it here:
http://www.dvdshrink.org/where.html