Why not a "Choose MP3 decoder" menu ?
 

it would be very usefull on some PC configurations (like mine) :)

Why that ? Is it something different about your configuration ? Tell us so we can learn more.

my soundcard doesn't support 48khz, but there are a lot of movies encoded at this rate
i want to use a decoder different than fraunhover's (or whatever was the name)

I don't have an 48000 khz sound card but I can wach movies encoded at that sampling rate. But I use Fraunhofer's codec that came with divx 3.11.