If you insist on freeware,SUPER is your best choice.You can search such software on http://www.google.com or http://www.yahoo.com
But in my personal experience,the freeware always have some problems more or less.its quality can not be guaranteed.
Why not try Pavtube Video Converter, which has comprehensive video input formats and output formats. It can convert video and audio files with comprehensive formats as follows:
Input formats: WMV, ASF, WMA, AVI, RMVB, RM, RA, MOV, QT, MP4, M4V, 3GP, 3G2, DAT, MPG, MPEG, MP3, VOB, DV.
Output formats: AVI, MPG, MPEG, VOB, MP4, 3GP, 3G2, MOV, WMV, FLV, DV, MP3, AAC, M4A, WMA, WAV, AC3, MP2.
Also it provides some unique and useful functions. Don’t worry about the conversion speed and the output quality, The converter works great with the two aspects, also could run in windows vista suitable.
You can find this program at this website: