EO Video is another tool that can convert Quicktime movies, this one converts the sound aswell.
I just tried it with 'The second renaissance part1' BUT since that quicktime movie contains TWO audio tracks (one for the first 10 or so seconds of sound and one track for the rest of the movie), EO only converts one: the second track... which results in total out of sync sound. I solved this problem by opening the movie in Quicktime and cutting the first 12 seconds (the duration of the first soundtrack is about 10sec) of the movie and then 'Export' to a new self contained movie and then open that new file in EO Video and encoding it. This works OK without the need to first decompress it to a large Uncompressed AVI.
EO Video can be found
here It's not free but they give you a generous 30 days try-out, full working version to test the program.
*UPDATE*
After watching the whole movie it struck me that the video is clipped for some reason. I've played around in EO video but can't find any way to resolve this... or change it. So now to make things 'easy':
I've converted the Audio in EO-Video and done the video conversion with RADtools. After that I muxed the audio and video back together in VirtualDub.