This is what I have been told from a couple different stores regarding the "warranty". The DS comes with a 1 Year warranty from nintendo. The only difference is if you buy one from the store and something goes wrong with the DS, you just bring it back to the store opposed to sending/mailing it back to nintendo. We have 2 DS's and we didn't buy the warranty on either of them, we just send it back to nintendo to repair.
HTH,
Michele
HTH,
Michele