Then what you are looking for is a DVD ripper, not a burner or converter. A ripper will do the converting for you.
Is this a commercial DVD or one that someone made for you? Because if its a burned DVD then all you need to do is pop it in and click on the drive in the My Computer window, then grab a .vob -> .mpg converter and you're off to the races.
Initiate discovery! Fire the Machines! Throw the switch Igor! THROW THE F***ING SWITCH!