Offhand, Bink tools (RAD video converter) will do it (edit: strike that, will only do to AVI; still might work for you). If you use it, be sure to look through all the options. I think the first time I tried it (and it's been several years since I used it) the resulting file ended up being huge. But I think I added all kinds of things to the conversion to try to increase the quality. Big mistake.
I need to do a few of these myself so I might try in a while a see how it works. Otherwise, maybe someone else will have a suggestion.
MediaCoder, SUPER!, and several others are free and get the job(s) done relatively easy these days. MediaCoder is fairly extensive in terms of capabilities and options. SUPER! is a pain in the ass just to acquire it; downloading it requires jumping through a few hoops from the source website, unfortunately. Can't say much else about it.