How can I convert avi files and other file types to WMV without a terrible audio offset?

I've been using Windows Movie Maker to convert avi files to windows media video format (i have all of the codecs installed so they are compatible with WMM) but the resulting file has a terrible delay with audio and video. The reason I want them converted is so I can put them on my Zune. It is very rare to find movies in WMV format and I dont have a very professional program that can convert them.