not really

The advertising world of digital photography emphasizes the importance of megapixals in the quality of a print. But there is more to the story than megapixals. The other part of the story is how well a camera produces a picture with the lack of "noise." There are high quality 4 and 6 megapixal cameras than can produce higher quality pictures than many 8 megapixal cameras because they produce them with much less "noise." It is in this area that you get what you pay for in the world of digital cameras today.

In most cases more expensive cameras will produce higher quality (less noise) images at ISO-800 than less expensive cameras will at ISO-100.

BTY, most digital ISO set by default at 250, not 100.