Lexar NOOOOOOOOO don't do it!! I have a 1ds mk2 and three Lexar 4gb 80x cards and one 2gb 80x card and the problems I have had!! lost images, corrupt files, images that look fine but when opened crash, all down to the Lexar card, in Lexar adverts they say "don't trust your camera with anything else" ha ha ha that's a joke, what they mean is "don't trust your camera with Lexar"
Sorry if I seem a bit angry but when you have lost important wedding images beacuse the compact flash card has a problem then I get angry, Lexar advertise that they are THE professional card, maybe but not with canon.
I would be interested to hear of any other Canon users who have had a problem with Lexar cards as Lexar told me that my case is "extremely rare" i'm not so sure!!
Stick with Sandisk, I will be !!