Try using
Dvdshrink for single layer dvd's, this is a great little tool for reauthoring the movie to make it fit. ( Read more on it) Now if your getting into burning dual layer dvd's I recomend using DVD Decrypter to make the copy, and Imgburn to burn it to disk. ( Read more on DVD Decrypter and Imgburn) And also don't forget to use
AnyDvD to neutralize the region codes and strip the copy protection. ( Read more on AnyDvD )