I'm getting ready to take a road trip so I thought I'd download some mp3 files to the 4gb SDHC card to listen too. There is ulterior motive for this also. I was going to route my driving instructions through the fm radio but it won't do this unless you're listening to music from the GO too. I've moved several mp3 files to the card but when I go to Jukebox it says there are no music files seen. I've got all the maps, voices etc on the device and just want to use the card for music. What am I doing wrong?