Yeah.....I got an iRiver player for Christmas, the salesman told my wife it would play nicely with Linux, and would play OGG Vorbis. Turned out that this wasn't strictly true (or even close). Some iRiver players will play ogg with a firmware upgrade. None play nice with Linux. They barely play nice with Windows! Three emails (the first two polite and seeking help, the third querying their interest in their customers and products) to iRiver...no answer!
Basically, get an mp3 player that will truly behave as a USB storage device, and use that. Don't belive the salesman. Don't buy iRiver. Or just use a laptop. I had a depressing experience!