Whisper fans the answer??

I find my HD box makes a lot of fan noise, as well as the PS3.  I understand PS3 is noisy, but I am a bit disappointed with my HD box as previous posts seem to indicate it depends on how lucky you are when you get allocated a box.  I have left it about six weeks now so am probably not in a position to ask for a new HD box.  So...

... are whisper fans the way to go.  I have all the equipment on a stand in an alcove in my room, which I think is ventilated sufficiently.  However, maybe if I put a whisper fan in the plasterboard wall behind the stand it will cool both HD and PS3 down so their own fans do not kick in so hard.  Is that how it works or will the fan just be a safety net to make sure the boxes do not overheat and die, and the boxes fans will still be working hard at it?  Also, how nosiy is "whisper" as I do not want to add to the noise.

 Any guidance appreciated.

 Paul