jtara - 6:00 pm on Sep 22, 2007 (gmt 0)

There are plenty of tools to do these conversions. Unfortunately, they aren't going to give you professional results.

If you want it to look good, always go back to the source (whatever the video was originally shot on) for each conversion. And use a high-quality, lossless source.

Converting from one lossy-compression format to another is almost always going to result is a poorer quality.