RWR wrote:
When I got my first digital camera I wondered the same thing, so I set up a scene outdoors with lots of fine detail and light and dark areas and, with the camera on a tripod, exposed the same scene at every ISO setting from lowest to highest, keeping careful notes. Close examination of the resulting images clearly indicated that camera's limitations. I would suggest you try the same, and let us know your results. :)
I do the same thing whenever I get a new camera, and I'm surprised everyone doesn't do the same thing.