In article <4hj65t$2tt@engnews2.Eng.Sun.COM>, toms@Eng.Sun.COM says...
[...]
>Actually I don't think I can afford the Nikon 20-35 zoom, so the
>choice is really between the Tamron 20-40mm or a Nikon 20mm/2.8.
>I already have a Nikon 28mm/2.8.
>Any comments/opions on this would be greatly appreciated.

I would get the really excellent Nikkor 20mm f2.8, especially if you already have the 28mm (though if it is the AF or E version, the 20mm
will give you a pleasant improvement in image quality). Personally, I find wide-angle zooms of limited usefulness, and not worth the
trade-off in image quality, size, and price.
Hope This Helps