CPU Temp question...please help

It's probably a simple question but I don't know the answer.

I've got a AMD Phenom 9950 quad core 2.66 Processor and 4 GB of Ram running Vista Ultimate 32.

I just downloaded Kaspersky antivirus software (had a virus crisis earlier) trial version to decide about buying the full version.

I'm looking at the temps because Kaspersky is constantly running and scanning and the hardware monitor program that came with my Bios (on disk entitled AMD chipset drivers) says a CPU temp of 36 degrees Celsius and system temp of 33 degrees Celsius.

I downloaded CoreTemp and it's saying CPU Temp readings are anywhere from 39-46. 2 part question:

Which do I believe?

What temps should I be worried at when idle? gaming?

phenoms give two readings, one is for the temps of the cores, the other is the 'overall' temperature of the processor. To identify cores use cpuid or everest software, if you dont want to do that, the cores are usually the ones with the temps jumping up and down while the overall temps is more stable