Converting from wma to mp3

[Pistonfest]

I have a folder full of tunes, but some are wma & some are mp3.
How do I convert the wma tunes into mp3 format, or is this not possible?

[FourWheelDrift]

Try - www.dbpoweramp.com/

[Pistonfest]

Why thank you kind sir, works a treat.

[Buffalo]

I'm led to believe wma are smaller files than mp3. Is there a noticeable change in quality..? Just my mp3 player can do both, but would be able to increase tunes per memory stick if so...

cheers