@ amubin
for this purpose, you can use SUPER, the most reliable and super fast encoding tool, and it is free. you can encode/covert any video format into another video format or in audio format, enhance its resolution, though not advised, reduce resolution to play it on you cell phone, and many more features. you'll love it, if you use it.
here is the link to download it.
SUPER ©
You can also use jetAudio plus for conversion purposes from video to audio. be sure your jetAudio version is plus VX not the basic free one which doesn't encode/convert files.
download its VX Plus (Paid) version from the following link..
http://rapidshare.com/files/39499495...us.VX-FOSI.rar
it won't require the basic version pre-installed for VX Plus. enjoy...