Question about temps of laptop, please help

So I recently just got a HP Compaq 8510p with Vista SP1 I was annoyed that the fan always spun and never slowed down after I played one game of anything so I checked the temps with HWmonitor and I noticed that there was a reading listed as TZ0 that was 70C and as far as I can tell it never moves no matter what I do. All of the other temps read fine as far as I can tell, the only hot spot is right under the touchpad where I believe the wireless card is located. The temps are as follows while idling:

TZ2_ 40C
TZ0_ 70C
TZ1_ 45C
TZ3_ 41C
TZ4_ 20C
TZ5_ 65C
Local 43C
Remote1 40C

core 2 duo T7300 temps are 45C and 46C
HD is 38C
Radeon 2600 is 20C

while playing a game the cpu will hit 75C and the gpu about 30C or so according to HWmonitor

Upon seeing this I downloaded speed fan and that told me the same temps except there was a flaming reading called ACPI that read 70C and never fluctuated so I assume this is the same sensor as the TZ0 in HW monitor.

Any thoughts on what this reading could be and if I should be worried about it?