OK, this can be pretty complicated, but two freeware utilities have made it much easier:
* DVD Decrypter. You need to set this in Mode/IFO and make sure to copy everything onto the hard disk. For performance reasons having two hard drives is very beneficial otherwise you thrash like crazy.
* DVD Shrink. You use this utility to shrink things so that a 9GB DVD-9 will fit onto a single layer DVD Writeable with 4.7GB available. The main trick here is that you can lots of the extras and keep the menu structure but replace the actual extra with just a single image. You can also take off the various audio sound tracks. It also burns the DVD backup for you.
Here’s a more general overview from Doom9.net – The Definitive DVD Backup Resource