HVX200 sensor is noisy, you can't do much about that.. you could play with scene settings, where black would have less noise, but in overall, hvx200 is quite noisy. I'm sure Barry could help you out more about this...
there are plugins for your NLE that go a good ways to minimizing the noise. http://www.neatvideo.com/
but as tomas said. the hvx200 is inherently a "noisier" camera than some people prefer.
Lighting Lighting Lighting...I was playing with mine in my editing room fire wired to my editor displaying on my 37" TV. Its amazing how even a area that is decently lit has noise. When completely lit, all the noise seems to go away. With my 300 watt camera light the noise was almost non existent.