I added mp3 support to fc2 by following the instructions on this link:
Everything appeared to go well and I was able to disable the placeholder [null] input plugin, and enable the new MPEG Layer 1/2/3 input plugin.
However, when I played an mp3 I got no sound at all. Also, xmms read through the file very quickly, going through a 12 minute mp3 in about 1 minute.
When I open up a game like Chromium I do get sound.