I am going to ask a stupid question. I use the regular SanDisk card-1G. What is the difference in these other SanDisk ones-UltraII/ExtremeIII ect. I guess I havn't been following these but I have seen them in the stores, but not sure what the difference was. Also, someone told me that some cameras you can't go above a certain "G", like a 2G card for example. I have a Rebel XT. Any suggestions or explanation of the difference of these cards? TIA

