If I understand correctly, the C2D chips are the first Intel chips to have temp diodes on the die itself, at the hottest point for each core. Therefore, there are 3 temps that apply to the CPU: mobo cpu diode, core1, and core2. The core temps will be higher than the familiar cpu temp reading from the mobo. For example, my E6300 temp reading from the mobo is about 30C at idle, while the core temps are about 41C. According to the Intel site, the C2D chips have a thermal ceiling of 61C, meaning stable performance is only guaranteed up until that point. As for the HSF, imo, you absolutely need to scrape off those 3 strips of thermal gunk and use something like AS5. As for the mobo temps, if you have a P5B Deluxe or a P5W DH Deluxe, you should remove the copper plates that are glued to the north and southbridge heatsinks (iirc, the P5B Deluxe only has this plate on the northbridge). These caps inhibit the proper heat dissipation from the heatsinks. You may also wish to remove these heatsinks and replace the awful crud that is supposed to be thermal paste, and use some AS5 there, as well. I got my P5W DH Deluxe's mobo temp down to 42C, from 48C, by doing the above.
One more thing, PC PROBE II is buggy as all heck, on my P5W DH Deluxe. Instead, I use Everest Ultimate to monitor all temps. The latest version can even read the C2D core temps, as well as all the expected diodes.
If you're interested in following the above procedures, heress a guide for the P5W DH Deluxe, most of which will apply for the P5B Deluxe.
http://www.xtremesystems.org/forums/showthread.php?t=106563
-phil