Leaving your notebook fan on all the time is defeating the purpose of the newer notebooks with power settings to increase battery life.

If you are worried about the humidity, use a Notebook Podium Coolpad from Targus (see their website) or similar raised platform underneath the notebook which raises the rear up to 2" and allows for a much better air circulation flow to the vents underneath.

Also, the tilt allows a better typing position and it is adjustable to 3 levels as well. This Targus Podium Coolpad is 29.99 retail but it can be found for less.