what criteria (or is that criterium..??anyway) makes a camera 'professional'? I was thinking about the classification of say the Nikons 3. The beginners D40X, the semi-pro or enthusiasts D80 and the 'pro' D200. If they have the same sensors, pixels etc, where is the line that crosses from one category to another? And why wouldnt an enthusiast not be a D40X user or a D80 a beginner or a pro?