How reliable are P4PE temps?

It's been very warm weather overhere and my PC is sitting in the attick, the hottest place in our house! It's been upto 28C ambient here last week and Sandra tells me the CPU temp was 66C (running SETI). Right now it's about 25C ambient and Sandra says it's 63C CPU, however my (original Intel) HSF is only warm to the touch. I'm constantly switching images of OS's (Win2kpro SP3 and Longhorn XP pro beta Build 4015) but they both display the same temps. My P4PE is revison 1.03 and has BIOS 1005...

As you can read in my signature by now, I got a Zalman CNPS7000-Cu and my temps dropped to 55C full load and below

P4PE has been known to report 5-10C higher than what it's suppose to.