You can use a Flash element to play MP3's... There are lots of free ones around, but the better ones are commercial...
I understand that the FLAMPlayer Module available at flamplayer.com is pretty good and it's free.
http://www.flamplayer.com/
Now that said.. be prepared for an onslaught of messages as to why it's poor form to have sound automatically start playing on a website!
Mike.