If you download NikonView 6 from the Nikon web site once it is installed
you will find two files in the folder where you installed NikonView to
(Nikon NEF Plugin.8bi and Nikon NEF Plugin_5x.8bi) copy them both to the
plugins\Adobe Photoshop Only\File Formats folder and you should be able
to open the files in Photoshop.
However, please note that it doesn't give you anywhere near the number
of controls which you might have in Nikon Capture. Another alternative
would be Adobe Camera Raw - but I think that might only be available as
an add on for Photoshop 7.
(Posted from the UK)