One this pic I didnt have the D2x formats but I have them now...D2x 1 is great for skin tones!! I have not heard that it helps with the Noise factor however.
I have seen and experienced that using Capture NX produces less noise than using CS3 and lightroom. The colors are better also...
Im now into the habit of converting all RAW files to a TIFF in Capture and then putting in CS3. This preserves all colors, sharpness and decrease in noise.