speedfan is popular and often updated, so it should be accurate
on an air cooled system, the HS can be as big and fancy as it wants, but if there is no air moving through, it wont cool very well. my intel C2D e8500 was hitting 45C idle at stock speeds with a stock HS. i then spent money on a new HS, a powerful 120mm exahaust fan and an expansion-slot exauhst fan. i installed the parts, covered over the side vents, and made a front intake hole by poping out a 5 in expansion slot covers. now all the air that comes into the pc goes past the HS. fanspeed reports about 40C idle after i OCed it to 4GHz. it doesn't look pretty with a hole in the front, but its under my desk. if you do the same ( as in lots of airflow past the HS) it should cool right down.
Read that guide.
After you get what's going on here is what I would suggest you start doing (settings in BIOS).
1. Set the PCI Express Frequency to 100mhz (so it does not automatically scale when you increase the FSB).
2. Increase the FSB to 400 MHZ (like the above posters said, you should be able to reach that at stock voltage).
3. Run Prime95 in large FFT/blend to check for CPU/RAM stability (if it crashes, you might need to adjust your NB voltages by a little).
4. If Prime95 is stable and your temperatures are good, then run Intel Burn Test and see if there's anymore problems.