And to answer part of your original question (not to mention furthing my ascent to guruship) – there is no difference in playback whatsoever between the card and the unit memory. However, when you add music, it will take longer to refresh the database, simply because there’s more data for the player to sort through.
I bought a Sandisk 16 gb card for about $30 on Amazon, and it works great. However, of course, “16 gigabyes” doesn’t _ really _ mean 16 gigabytes, to Sandisk or to anyone else selling storage. Just a pet peeve of mine.
A very convenient loss if you’re selling, and a very incovenient loss if you’re buying. Didn’t know it was seven percent – that’s a LOT! Like I said, pet peeve.