Laptop running at 590 MHz

My laptop has a pentium M processor which should run at 1.6 GHz, but it usually runs at 590 MHz. this i believe is because the power management comes to play. On linux, this can be changed by 'echoing' to a tunable variable in /proc (i vaguely remember doing this). Now how do i do this on Windows. Yeh i also run Windows XP on my laptop and i need to make the processor run at 1.6 GHz instead of 590 MHz. Ok id google and try to look for some tools that can help me do that.