Nikon currently produces about 6 different 50mm prime lenses, but they don't make a lens called the 50mm DX. There are a lot of discussions in the forums already about the comparisons between some 50mm lenses, so it's definitely worth doing a search to get a variety of feedback on this issue.
From my personal experience, my 50mm f/1.4D has been a great match on my D7000. The autofocus is decently fast, and it is sharp for any aperture after f/2.8. The autofocus is noisier (louder) than the newer 50mm f/1.4G lens, and you have to flip the AF switch on your camera to go back between AF and MF. But the best of all, it's cheaper than the G models. If you get the f/1.8D, it's going to be even cheaper.
You should also look at the 35mm f/1.8DX as well. (This may be what you were originally talking about). It's much more usefully focal length for me than the 50mm on a DX camera like a D7000. The 35mm f/1.8 is the lens I use the most on my D7000.
Hope this helps.