Everything you need to know is right
HERE
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Actually, that article is pretty true, especially for me. I am currently on my 5th digital camera since 2001, although I didn't take as many steps as the article suggests.
My first digital was a Nikon Coolpix; one of those "hinged in the middle" things. That camera got my feet wet in digital after many, many years in film. I shot pictures, built my own website and had a blast learning digital. But, there were limitations to the CoolPix, so I began looking at a better camera.
Next came a Fujifilm Digital ZLR, non-interchangeable lens zoom. It was great, until the limitations. So back to looking at better cameras.
Next was the Nikon D40. I love that camera and still have it. I found the limitations and started looking at better cameras, but kept the D40 and use it in my camera "system".
So, I added the D90, and then recently, the D7000.
I use all three Nikons, for different uses. And I am adding to my system, so everything works together.
So, with that being said, my suggestion is to buy the best you can afford right now while looking "down the road" to how this purchase will fit in with additional lenses, bodies, etc.
Good luck with your decisions and let me know if I can help? We can always meet someplace if you want to look at different bodies, lenses, etc.