SuperGroove, here's how you get Winamp to convert mp3 to wav:
1) Launch Winamp
2) Go to Options, Preferences, select "Output" under the "Plug-ins" group
3) Make a mental note of which Output Plugin is selected in the right hand pane (Waveout, DirectSound, etc... NOTE: it?s usually ?Nullsoft waveOut plug in"

4) Select "Nullsoft Disk Writer Plugin..." in the right hand pane
5) Click Configure (and select the directory where you would like the *.wav saved)
6) Click the "Close" button
7) Double click the mp3(s) you want to decode to *.wav (you won't hear anything and the EQ Graph will bump along until Winamp has processed and saved the entired *.wav)
8) Be sure to change the Output Plugin back to waveout or whatever you noted mentally before or you will keep decoding and saving wav files everytime you play something.