amilo 3438g - power or fan management does not work

Hi i own a fujitsu-siemens 3438g, using windows XP, i was able to run it in
silent mode (not much fan noise), and the fan stopped automatically when not
needed.

I now installed Windows Vista on my computer, and the FAN is always on, i
hate it... a noisy buzz - infact if i dont find a solution anytime soon, im
back to XP :-(

i updated the BIOS with the newest version, the Chipset drivers as well from
intel.

Im not sure what causes the problem, but it must be the way the bios talks
to the new windows.

If anyone has any idea what to do from here, I would be happy to hear...