Here is an Encore FAQ entry with one workflow and some utility suggestions. There are many more applications that will rip from DVD.
You might first try copying the .VOB(s) to your HDD and changing the file extension to .MPEG. This works in most cases, so long as the DVD's Menuing does not get in the way. This is normally manifested in problems with the first .VOB.
This ARTICLE might give you some background on .VOB's.
Another workflow would be to hook up your DVD player to the input connections on your video camera. It will need to have pass-through capabilities. You can then possibly Capture in PrPro, but you will NOT have device control. However, it's easy to manually start Capture, then start the cued up DVD player.
PS CS4.1 will Import 100% compliant DVD's, but that upgrade is not free.