Last time we went to WDW (2 years ago) we spent so much $ on water. This time around (Feb. '05) I want to bring bottles of water with us in a backpack. Does anyone have suggestions on how to keept the water cold? I heard you can freeze the bottled water and then take it that way. I will only have a styrofoam cooler and ice from the resort -- will that freeze the water? Thanks!