Oh, have not tried this one... yet!
I have tried many many video converters. The best one I've found so far is AVS Video converter:
AVS Video Converter - a universal AVI to MPEG Converter, AVI to DVD Converter.
It does unfortunately come with a small price tag, but it is well worth it IMHO. It is the only one that I've found that no matter what video format, size, compression and frame rate you convert it to, it always manages to keep the audio and video in sync. There are so many video format options available with this tool, and it even comes with it's own mini video editor. Look out for the bundle option to this tool, which turns out to be cheaper (for some strange reason) to the converter alone.