Have you listened to any of our podcasts? They're all MP3s ripped at 80 kbps mono and sound completely fine. Stereo is overrated anyway.
Yeah Right Radio said:
Have a look at aac+ vs. mp3 streaming. Better audioquality in relation to the bandwidth used, so you can even serve smartphone users with a limited bandwidth with an acceptable to good sound! The only downside is that one needs an aac+ capable music player which are less common than plain mp3 music players, but the major players like VLC, Winamp, iTunes etc support it. Have a listen to http://yeahright.getmyip.com:8000/listen.pls with one of those players and check out the soundquality!