Is more than 120hz for a 42' over kill?

You will be fine with the 120HZ. Keep in mind that this is only on LCD or LED tv, to reduce the blur motion when watching fast action sports or playing video games. Go online to Home Theater Magazine and read the reviews on tv, along with the pro and con of each technology. 3D has not been up to far with consumers, due to lack of software in the market today. There are only about 40 titles in 3D and they are mainly animated, beside that you also need a 3D blu ray disc player, 3D blu ray disc movie and 3D gles to watch 3D in your 3D tv. Hope this will help you out.