After two months with my 3rd E6400 I am officially DONE with Dell Latitudes

By any you mean Flash? The problem you face is 100% Flash fault.
It doesn't use the GPU as it freaking should. I program Flash since Flash 4, before youtube and before it could even play any sort of video.
The fan kicks in, because Flash is vector based software.. basically everything is treated as vectors, so that is VERY intensive on the northbridge and CPU... technically it SHOULD use the GPU as the GPU is DESIGNED for vector rendering. But it's not.

Macromedia are the one that invented Flash.. it was planned to support GPU rendering (as well as 64-bit). Sadly, these were canceled since Adobe aquired Macromedia.
Now, Nvidia is pushing Adobe to move their butt, but knowing Adobe lightning speed development... maybe your kids might be lucky and have such feature.

As the northbridge and CPU is more powerful then your old laptop, they go at max speed which produces more heat, which results in having you fan kick in.
All Atom based netbook can't play Flash super smoothly unless the animation is very small.
I am at university, and just by hearing fan from people laptops, you know they watch a Flash based video (or play a game).

I won't deny that this laptop fan kicks in a little too early... but all it can do is slowdown the inevitable (fan will kick in at some point.. maybe after 10min maybe after 30min of video.. but it will kick in).

 

Judging by this thread, there seems to be some progress.

John