How can I convert a .ogg file to a .mp3 file, so I can send it to a friend to play on windows?
You could output the .ogg into a .wav file. Then encode that .wav file into a .mp3 file. It's been discussed before. I posted a link to a site that has a script to automate this. People here have said this will result in poor quality, if I remember correctly.
Anyway, why not just send the .ogg file to your friend? Winamp plays .ogg files these days, or at least since version 2.9x.
dex