I am a beginner and want to buy a good, but fast camera. I have looked tiredlessly for a good camera and think I have narrowed my choices to the Canon Powershot SD750 and SD850. Besides the little better pixels and zoom, I don't have enough knowledge to know which camera is the better buy. Keeping in mind I want a camera that is pretty fast, is the 850 worth the extra $100 or will the 750 do the job. thanks in advance.