For those of us in the MAC world....I've used MacFlac. It's a freebie and has worked fine for me. Also for the MACers when getting a sound file that is .wma tagged....it will not play on iTunes for the MAC. iTunes for Windows has the converter built in.
I came across a program called Audion3. It used to be shareware, but if you go to the website
http://www.panic.com/audion and under downloads is the player/encoder. There is a registration number provided that you input when you load the program....the directions are right there.
I take the .wma files put them in an Audion playlist and hit encode. You can set the preferences to mp3. Then you can take them into iTunes and do a full iTunes conversion under Advanced.
Hope this helps.
Cheers