Read the instructions again. MP3 support kicks in when you finish it's install or setup. You missed a step somewhere.
For some reason my RIO player will not allow the transfer of Windows Media Files (it has in the past). MP3s are no problem. Everything that I have gotten from iTunes or recent Napster will no longer transfer but anything I have transferred from a CD is no problem. I downloaded CDex but it will not recognize anything but MP3s, and only to convert to WAV. It won't convert anything to MP3. I feel like my Rio is now worthless. I run on XP and have a Rio Forge. Any recommended course of action? Thanks very much.