Where can I get a Free sound file converter?

I need a file converter to listen to certain files in .mp3. I have .wma files that I need to be mp3's so I can use my other program to edit something. Basically, I want to listen to a couple of select songs reversed, but my program doesn't use .wma's. So, I need to convert these .wma's. to mp3s. I used the Switch downloads, but my trial ended.