You might try this:
http://www.cooolsoft.com/
The Power MP3 WMA Convertor.
I use the old version which works pretty well. Converts "seamlessly" between MP3, WMA and WAV.
Also useful bit of kit is here:
http://www.mp3doctor.com/
This allows you to "tweak" MP3 and WAV files, including both the digital audio and the MP3 ID tags.
Good Luck,
Regards,
LD Max