Can I trust SiSoft Sandra reported values

I'm running a AMD 64 3200+ VENICE S939 with its stock cooler. My mb had a program called PCprobe that reported CPU temperature. With FS9 it reported about 52 deg celsius. I have updated my BIOS so this program won't work. But I found that SiSodt Sandra also reports the temperature. I have also replaced my QTec PSU with a Corsair HX520W and my fanless case with a new case equipped with two 120mm chassi fans. I was expecting a cooler CPU but it's reported as no more than 42 deg celsius in FS9. When I OC my CPU from 2000 MHz to 2200 MHz the temperature only rose one deg celsius. Could there be something wrong with these figures? Could differebt program report different temperature values?