Tamron 70-300 or Nikkor 55-200 vr?

I have had very good results from Tamron lenses. This one is optically as good as the Nikon ~ many reviewers rate it better) and they have the same maximum aperture; so the question comes down to longer fo cal length vs stabilisation. I have an 18-270mm stabilized lens and a 28-300mm non-stabilized lens. In most cases, I can hand-hold either one for bird photography quite well, and even pan birds in flight without difficulty in reasonable light; and at 65 years of age, my hands are probably not as steady as yours. Have a look here for some examples: http://www.photoartgallery.com/artist/DavidaRich The macro function gives 1:2 magnification...not true macro, but handy compared with the Nikon, especially given the longer focal length. The "standard lens on your Nikon already covers much of the range of the 55-200mm lens, which could reduce the potential versatility of adding a second lens. a 300mm lens on your D40 is equivalent to a 450mm lens on a 35 mm camera; the 200mm is equivalent to 300mm lens. That is a significant difference whether you are at the football field or in the field, and for me, for the use you are talking about, it would be a deal-sealer.