Speed fan does work to some degree, but it does not estimate the temperature by the speed of the CPU fan. That would yield horrible results never mind be completely wrong if you switched to a fan with a higher RPM. All temperature monitoring programs use the CPU's internal diode for temperature reading.
Download Coretemp (http://www.alcpu.com/CoreTemp/
) and check the temperatures. In Speed fan it is hard to find the actual CPU temperature. You think the CPU is one temp but you get a new program and find out its wrong.
And don't even think about overclocking on a laptop AT ALL. A 400Mhz increase is a LARGE increase for any CPU never mind a laptop. Also please state your temperature in Celsius as its more of the standard. 40C-55C is a good temperature for most CPU's.