I know the N-card is a nice, cheap alternative for a flash cart, but I have a few questions about it's abilities.. Does the N-card support sleep mode? Can the N-card play music (mp3's), even in sleep mode? What's the advantage of an internal battery? I see a lot of people listing that as an advantage, but I think it's bad cause it eventually dies. And lastly, how long DOES the battery (years?) and save files last? And are the save files kept alive as long as the battery is running? Thanks for any help, cause I'm planning on getting a DS and a N-card soon..