I just got the 4gb card and sd adaptor reader from earlier mentioned Ebay seller in this thread. I didnt even need to format, just popped it in, worked right away. I put 3.2gb of mp3, vids, and just about anything else i had to test the storage. Works great, perfect. I noticed a very minimal speed loss, but id say its the same speed as the 2gb i had.

Hope this helps.