People are saying the class 6 cards are better for data transfer, but I don't think anyone's been able to verify this yet on the DI in terms of reading the data.
However, I'd stay away from the SD cards that are "made in China" and go with actual SanDisk cards. I bought one of those ebay ones for like $15 for a 16gb and would get error codes on my Storm trying to playback media.
