That pretty much determines how many pixels you need.
IMO, it's always best to get the best camera you can afford, but that assumes you are serious about photography. If you want snaps for the web, you don't need a 7megapixel camera.
Between the two, which camera should I get? yes the 500 has 7.1 megapixels, but is that even necessary. It has a few more shooting options and scene settings, but I don't know if it will make a difference. Any suggestions?

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