confused on which temperature is what?

here is a screen of a few different programs displaying different temps for everything, but i don't know which one to believe.

the one on the right is the asus pc probe, it says cpu is 28
however the black one in the back is the amd overdrive utility, it says its 17.5
then speed fan shows both as temp1 and core.

i want to overclock my cpu, but i want to know which temp is the one i need to look at. a 10 degree difference is a big deal.

I would suggest using RealTemp or CoreTemp over any other temp monitoring software.

I unistalled pc probe sice it showed 10°C above ALL other progs. Dont think if it was true since both coretemp and everest showed the same temps.
You'd better follow matts advice for realtemp or coretemp

ok ive installed coretemp. its giving me the same temp as most other programs so im gonna go with that. it also has a nice addon for my g15 keyboard