Speedfan allows you to adjust how your laptop fan works -- what temperature it comes on at, how long it runs, the speed at which it runs...
http://www.almico.com/speedfan.phpAre you sure the fan isn't just noisier than it used to be? Over time, they do wear out and get noisier. Also if the fan is coming on in response to processor temperature, the thermal paste between the processor (or video card/chipset) and the heat sink may be drying out and not making good contact anymore.
Also, if you've updated the firmware, sometimes laptop manufacturers will adjust the temperature when the speed comes on.
Where did you get the laptop? Is it under warranty?