I've used Nero Vision, which transcodes a 2 hour movie in about 1 hour, 10 minutes. Most of the time, the movie is ok. Sometimes, though, the audio track gets shifted so it plays ahead of the movie. This problem lessened when I removed the Nero Plugin Pack, but it still breaks some movies.
I've tried Roxio MyDVD8, which transcodes a 2 hour movie about 3 hours and 20 minues. This works perfectly every time, but it's quite slow.
Any other recommendations? I don't mind buying a good transcoder if I know it'll be quick and error free.