SUPER can do this conversion. It is a free program. http://www.erightsoft.com/SUPER.html
You’ll have to wade through three pages of their propaganda, but the download link does exist…bottom of page 3. I just can’t link it directly.
Quick Media Converter is a new program that has this capability, but this program is still in beta. I’m trying out an xvid avi to wmv conversion right now with it. Will post back with results.
Here is a link for the program if you want to look at it. http://www.snapfiles.com/get/qmconverter.html