The HV20 won't be a lot better... if any at all. HD cams in general need quite a bit of light, and that's life. If the lighting in your home is not bright then you will have to consider a lamp for your cam.
In places where I do a lot of shooting, I have actually increased the lighting. I have DAYLIGHT fluorescent bulbs in the basement (gives beautiful indoor shots) and I have a 500 watt hal. floor lamp for the living room.