Every now and then someone brings this up on one forum or another...
Basically, the actual CPU temp doesn't matter, because you aren't cooling the CPU. You're cooling the water, which is cooling the CPU. So, you monitor water temp, since when it rises then your fan speed needs to increase to cool it down. If your CPU temp rises, then your water temp will rise (actually quite quickly if you place your sensor right), so you don't really need to monitor CPU temp.
Does that make sense?
If you really are set on looking at the CPU temp together with the others, then maybe try using
www.samurize.com.