I find 'gkrellm' useful for collecting the different sources of system data.  
It collects the ACPI data from /proc, uses 'lm_sensors' to detect and collect 
data from chips on the different motherboard buses and 'hddtemp' for the 
SMART hard disk temperatures.  Some information on the ACPI data is in 
chapter 12 of the pdf manual at "
http://www.acpi.info/spec.htm".
David.
p.s.  My /proc/acpi/thermal_zone/THRM temperature is always 40C but I have not 
worked out why.  It could be a bios or linux kernel error.  It could also be 
a trip temperature for the bios fan controller.