I don't know what kind of experience you have, but as a beginner I have learned that even a mediocre camera can produce excellent images when used properly. Both those cameras are excellent, and if you are a beginner like I am, chances you will be producing very similar images with both cameras.
I was debating the same thing when I got my D50 and decided on the Nikon because it was slightly cheaper. I put the money I saved towards good lenses and never looked back.