First if you look around you can find the software for $100.00 ($99 to be exact)
Second NC (comes with camera) and NC3 does come with a plug-in for opening and manipulating NEF images with Photoshop 5 or 7 (I tried both)
Third if you have some issues with the degrees of sharpening and contrast offered by the camera (too much or not enough) then NC3 will not solve this problem. You'll need to open in Photoshop and manipulate there.
I've tried many combination and while I am not a fan of Photoshop (I like QImage much better and the price is amazingly low for what it does - hallas no NEF yet) I must admit that it does a better job at controlling sharpening and contrast based on my experience.