I would go for the Nikkor. I owned one for 2.5 years and sold it recently (to get new 24-70, 2.8). I am using the Nikkor 18-135mm in the meantime, untill I sell the D2x (to get new D3).
The Nikkor 17-55mm is exquisitely fast and quiet. Superb built quality with dust seals etc.
the 18-135mm is much slower and hasn’t a great build quality (plastic mainly)
I do not know much about the Tamron range, but I heard they wouldn’t last as long.
If I were you I would go the extra mile and save a bit more to get the Nikkor, the images are sharp throughout even at 2.8 and at wide angle. very little distortion.
Good luck with your choice & tell us how you get on.
I have reduced the price to 2499 to match the price of used D2x’s (professional use) at “Conn’s Camera” shop. You can of course buy any on ebay, but at least this one you can view before you buy and has the actual mileage displayed. Additionally you will have the certitude that this camera has not been heavily used.