Fluctuating Temps from Hardware Monitor, Odd?

Using CPUID's Hardware Monitor on my AMD Sempron 2800+ with stock cooling, I'm having a hard time believing the CPU temperature results that I get are genuine. I have three values, TMPIN0, TMPIN1, TMPIN2. I don't really know for certain where these sensors are or even if they are reading my CPU, I'm just taking an educated guess from some of the results I've seen other users post. The values of sensors 1 and 2 don't ever really change regardless of idle or load, which I find kind of strange, but what strikes me as the most odd is whats happening with TMPIN0. The value fluctuates in such a random manner changing up and down by 20-30 degree C differences by the second. It seems to be randomly picking numbers between 1C and 60C. Also I get minimum value of -18C, after leaving HWMon running for hours, which I just can't believe is any sort of accurate. This happens in idle state as well as full loads so I'm left wondering these things I hope you folk can address for me:

-Is this even my CPU temp?
-Do I need to calibrate somehow for accurate values? or
-Has the sensor been damaged in some way?

Help appreciated and I wont mind if you laugh at my dinosaurbox.


CPUZ Dump: http://www.psilocybernetic.com/cpuz.htm
Hardware Monitor Screenshot: http://www.psilocybernetic.com/hwmon.jpg

Not connected to anything huh? I would have never guessed that.

Thanks nukemaster.

SpeedFans older versions used to have that. I had something on mine at 100C+ and was trying to figure it out since I know I would have seen smoke.