Thank all of you for your answers.
The acpi THRM doesn't work here. It always gives me 40 no matter what. Don't know why... Maybe it's something to do with the motherboard.
As for lm_sensors:
I ran sensors_detect again and I can now get the CPU temperature from the w83627dhg-isa-0290 module.
sensors_detect does however detect another sensor (I suppose in the CPU) that requires the coretemp module.
Apparently, this would allow me to get the temperatures of each core independently. Not that I care much about it, but I'm just wondering if these would be more accurate (I'm getting a maximum of 35C with two instances of mprime running, which I thought was a bit low).
I don't seem to find the coretemp module though... or at least, I don't know which patch to download or how to get it running. It is this coretemp module that is (I think) included in the 2.6.22 kernel.
Because I am getting the temperature with the other module, it's not much of a problem, but I was wondering if anyone got the coretemp one working for Intel CPUs with two cores.