Inspiron 1150 & cpu speed

I activated the power scheme 'Always on' so that SpeedStep technology is not used. And indeed, the System Properties list the processor as a Mobile Pentium 4 2.8 GHz running at 2.8 GHz.

However if I run the utility found on www.h-oda.com to monitor the cpu speed, it says the cpu is running at about 1.6 GHz. Only if I run e.g. huge Access queries it boosts to 2.8 GHz but inmediately afterwards falls down to 1.6 GHz. Should I be worried or not?

Thanks in advance

Chris