I am looking at purchasing a Sony Cybershot DSC-P150. The problem I am running into is that I would like a 512mb memory stick. There seems to be two options, a high speed and a pro. The high speed is quite a bit more expensive. Does anyone know the big difference? From what I have read, my general understanding is that one records memory faster than the other. With my simple shots here and there I am thinking i don't need the expensive one, just the standard. Can anyone help with this? Thanks in advance.