Interpreting SpeedFan Readings

I just got SpeedFan 4.37 for my Windows partition on my MacBook Pro (early 2008). Can someone tell me which areas the readings are measuring?

My Understanding (correct if wrong):
GPU: Graphics Procesing Unit
HD0: Hard Drive temperature
Core 0: CPU Core 1
Core 1: CPU Core 2
Core: ???????
Ambient: I guess this would measure room temperature if my computer had that?

SpeedFan is a reliable and accurate temperature gauge, right?

BTW, hit a high of 77 degrees celsius (170.6 degrees Fahrenheit) while playing Civilization 4 on the Windows side. My searches show that these MBPs can handle up to 95 degrees Celcius without getting into trouble, right?

Are there particular areas that are more heat sensitive than others, like the GPU or Hard Drive?

~Scott