Make MP3 Files Smaller

[iisdev]

I recommend Audacity as well. Since it's just a ringtone and not a song it doesn't have to be in stereo so make sure you choose mono for the output file.

You can check out pictures of the interface and download it here:
http://audacity.sourceforge.net/

[catalinux]

I am surprised none of you recommended dbPowerAmp. Test it and you might find it useful for sound conversion. Please note that you may have to download some codecs before the file conversion (depending on the format you want to convert to), easy task nonetheless -- the link to the codecs central is on the download page.