Answers: Audacity is great. You do call for to download the lame MP3 encoder too.
Audacity
http://audacity.sourceforge.net/
bowdlerize: lol 12 secs ahead of me yep what the above said ^^^
and heres lame encoder...
http://lame.sourceforge.net/index.php
Audaicity is the best .It comes near effects.But you want to download the MP3 Codec.