I just gave it a try. It is very interesting that ATITool can now show the temperature of an Nvidia card!
But, I am back to Riva! I prefer the higher resolution of the graph that shows the temperature log for Riva. The temperature log of ATITool goes from 30 to 90 and it is very small. So, it is not possible to tell the difference between 60 and 70!
ATITool is much simpler to install and configure. But, it seems like RivaTuner is much more powerful.