If you caught that little dance, there, Somebody posted trying to advertise their video converter -- on an audio forum...
Anyway, you can use the "lame" plugin to create nice MP3 exports of your work.
http://audacityteam.org/help/faq?s=install&i=lame-mp3
I would recommend moving over to Audacity 1.3. This whole process is a lot easier and faster in 1.3 than it was in 1.2. You can install both on your machines as long as you only open up one at a time. Audacity 1.3 Projects will not open in Audacity 1.2. WAV and MP3 files should open up anywhere.
I'm going to continue in 1.3 because some of these tools don't exist in 1.2.
Change Audacity Preferences to 44100, 16-bit, Stereo or maybe Mono depending on your microphone and capture system.
Convert to mono. Track > Stereo to Mono.
File > Export > MP3 > 32Kb.
You can usually ignore the metadata panel, or pick "best compatibility" and then don't fill in the forms.
See if that's a small enough music file for you. MP3 at 32 is right on the edge of being able to hear sound damage on a mono show. You can go lower if you want, but the quality will start to gargle if you go too far.
If the client can handle AAC sound, you can have the same quality at about half the bitrate; 16 to 18. AAC sound files are not universal and you need to know where your files are going.
Koz