Peter, this is my first dslr, so I have no idea how many images I can expect to get on a 4 gig card. Any guesses? I could get about 500 on a 2 gig card with my old Nikon 4200 4mp point and shoot, but I bet there's lots more info associated with these, yes? I ask because I may need to keep filling the card during the trip and download when I'm back.