Here's a link with some side-by-side,real-world comparisons of one of the most-overrated lenses with one of the newer, better, designed-specifically-FOR-DIGITAL lenses. http://forums.dpreview.com/forums/read.asp?forum=1020&message=17192663
The side-by-side comparison photos show the Nikkor 28-70 AF-S compared with the Tamron 28-75 f/2.8 Di. The Di stands for Digitally Integrated.
If one can live with a non-AF-S and a non-Nikkor lens, one can have another thousand dollars to spend on something truly useful, like some studio flash units and light stands and umbrellas.