I have read through all the posts I can find and didn't really see the answer to this question. (However, I have found lots and lots of info that I never considered!!) How do you tell the difference between brands or even within brands, not size but speed? For example, SanDisk has 2 (or more) cards that are 512...one is simply 'SD 512' and the other is an 'SD Ultra 512'. I don't see any other numbers on the packaging to be able to compare. I an needing to buy a new memory card (SD) prior to my WDW trip because I am not taking my laptop with me on vacation since it belongs to my employer. I was going to buy a 1GB until I saw several suggestions regarding 'if your card goes bad, everything is lost'. Now I am thinking of buying 2 smaller cards. Please advise. I have compared brands on-line and several local superstores but don't seem to be able to compare the cards.