Thanks for the reply. I found out on the Sandisk website that the card is compatible with my camera. I also found out on another forum that there will be very little difference in write speed in my camera. But I can't lose: With the rebate on 3 2Gb cards they will come to $25 each, so I think I will get them.
You won't see much speed improvement on a Mark 2 body but copy time between your card reader and your computer could be shorter (depending on your card reader and connection).