well coolbits is integrated to nTune. So for oc'ing it doesn't matter which one u use, since basicly it's the same thing. nTune has some other stuff too, but nothing too important, coolbits is all u need.
You can do just about everything with it. I'm not exactly sure what or how it does it though. If you are going to be overclocking your cpu/ram just stick with the BIOS. For videocard I suggest rivatuner.