I have got 2 CF cards for my Canon EOS 400D. The two I have are Ultra 2 ...2GB & Extreme 3...4GB. Today I tested in RAW + Jpeg together & the results were not a great deal of difference. I could take 8/9 images with both cards in succession then it cut out for about 12 seconds while it wrote to the card, before I can take anymore. The Extreme 3 lets a few odd shots be taken as it's loading the Ultra 2 just a few less. I expected the Extreme 3 to be a lot faster. Today I was going to take The Red Arrows taking off from Bournemouth Airport. They take of in 3 - 3 - 3 - 2 formation with only a couple of seconds between each one. Because of this I had to take them in Jpeg in order to get several shots, several times. Had I done them in RAW + Jpeg or even RAW I'd have missed most of the Arrows because of the time writing to the card. I expected better than this with an Extreme 3 card. Is my card writing fast enough? To me it seems there is not a great deal of difference between the Ultra 2 & the Extreme 3.