I was able to capture several good lightning shots this past weekend with my brand new D7000. Love this camera and all the little things it can do. I recently got the book sold here Mastering the D7000 and it was worth it just for a few little tips I have already employed. I use it nearly every time I shoot and continue to learn more.
Anyway, you can check my gallery for some of the newest lightning shots. All were processed using Capture NX2 as well.
Great shots. Just an FYI, if you shoot at f/20, you're very likely to see whatever dust spots are on the sensor. These can be easily "cloned out" or erased via Capture NX2. But there are a few there. Check the upper left for instance.
It will be virtually impossible to have a pristine sensor for very long. But apertures like f/20, f/28, f/32 will really show dust wise what might be invisible at f/8.
One option, when you need LONG exposure, is to set your lens at f/8, shutter held open, using a flat black card over the lens to make and then cease exposures... It's an old trick useful on fireworks too.