i have just moved up to a 40D from a 20 and i am very pleased with it...only problem is whe in any of the manual modes i can only get 6 shots from the buffer then it slows down! i am running on full RAW mode and have a Extreme 3 sandisk 2.0gb card in so should be no problem. book says i should have a17 in the buffer before shooting how comes i only have 6? and i can't figure out for the life of me how to sort it help?

