Hey, I just received a new Canon PowerShot A540 for graduation. I will be going on a missions trip to Africa soon for 17 days, so I need to make sure that the SD cards that I have hold enough pictures, as I won't have a computer to transfer the pictures to. The camera came with a card with the number 16 on it, and the person who gave me the camera also gave me a 128 MB card. Approximately how many pictures do you think I will be able to take with that much memory? Thanks!!