To create an MP3 audio file in Lenny, you need to install the proper package to encode them. I suggest you add the “debian-multimedia” repository while you are at it. Edit your  /etc/apt/sources.list and add:

deb http://www.debian-multimedia.org lenny main

run

aptitude update

then install the gstreamer lame encoder:

aptitude install gstreamer0.10-lame

Then you are done. You can launch soundconverter and convert formats to MP3 using VBR and other technologies. You can also use sound juicer to Rip CD’s