Macbook fans on alot when connected via DVI...Problem?

[will0407]

I have my macbook hooked up via dvi to a formac 20" display. I've noticed the fans seem to be on alot of the time. I use it in 'clamshell' mode, although once ive started it up to just display on the 20" monitor, I do open the screen as I've heard it gets quite hot in clamshell.

Should I be worried that the fans are on a lot? I have my MB sitting on a griffin icurve as well.

 

[Jiddick ExRex]

My guess is because the GPU is used more handling more screen estate, it also gets hotter, and the MBP gets hotter as well...

I have found myself to have more apps open the more screen estate I have, so that might be it as well...