If you install ffdshow tryouts (a fork of the original, yet dead, ffdshow project), you can encode to a variety of MPEG4 standards: http://ffdshow-tryout.sourceforge.net/download.php
Also, my new policy as of July 09, 2009, is that I will assume the asker is using Windows unless otherwise specified. I don't like answering the same question three or more times for various operating systems just so I can cover all the bases. Therefore, if you use some other OS, please edit your question and say so. Otherwise, I will leave this response as it is: intended for Windows.