This post is certainly obsolete...
Mplayer has changed the syntax for pcm (wav) output. The pcm -aofile <filename> options has changed to -ao pcm:file=<filename> which doesn't like dos filenames (c:\bla\...). so I'm using a real hack to make a tempfile in the current directory (for windows only, *nix works normally). This script uses the syntax for the newer version of Mplayer, if you need the older syntax comment out the current method near line 286 and uncomment the one above it. This should be pretty clear when looking at the code.
./audio_conv.py -h ./audio_conv.py -i "*.wma" -r --to-mp3 --dry-run ./audio_conv.py -i "*.wma" -r --to-mp3 ./audio_conv.py -i "*.wma" -r --to-mp3 --normalize --delete