Both devices (really just one device with either samsung or pioneer skin) support Napster .  The device has a buffer, but if you hear something you like and want to download a "clean" and full quality copy, you can hit a button, and next time you dock it, it will grab it for you from napster.
 
 this is a natural connection -- XM and downloading.   You get exposed to something new, you tag it and download it.  Otherwise, downloading, you either know what you're looking for or its very hit and miss.