if you use mac, there will be a ware called "Easywma" I use that a lot, especially when i get songs from my friends.
If you use PC, i think that will automatically re-encode for you when you drag a .wma media format into your iTunes.
By the way, it seems that Easywma is a shareware, but you can still use it to convert .wma->.mp3. If you have difficulties using that software, i can email you one of mine. I downloaded it before it becomes shareware, which means a very long time. So it still can convert .wma->.mp3, but loses some new features. But it is a freeware, that is what i concern the most.