I've actually just picked up a D80, Tamron 28-75 2.8, and Nikon 70-300 VR as a starter kit...only yesterday, so I can't yet tell you how the combination performs
Outdoor shots seem to be pretty forgiving due to plenty of available light..I've seen great shots with everything from the 55-200G to the 70-200VR
I'd recommend seeing what kind of results you get with your 28-300 before rushing out to buy more glass.