[K.S.H]

I got a free one (512mb) with the 30D and compared it to the ones I already had and it was much faster at writing to the camera, I got told the best raw software for the canons is capture one and came across Picstop doing a free licence with Extreme cards so I bought another as the 512 wasn't big enough.
Suppose it depends on the cards you are using but they are certainly faster than the ones I had previously.
Heard some good reports about MrMemory own brand CF cards
2GB 133X PRO Compact Flash Card
for only
£14.99