um to help cooling, use Speedfan, for example you said when doing light tasks the fan doesn't turn on causing it to heat up and then cool down once the fans come on.
Well you can now tell speed fan to turn on the fans at a low RPM, like at 38 degrees and help cool it overtime, and once the temp runs into the 45 degree range tell the fans to speed up so it can cool it back to a lower temp.
you get it?

hope this helps,
As for designing laptops, hehe, dude we all wish laptops were silent, cool and thin and light and more.
But all laptops have thier flaws, the user is the one that has to live with it and try to make it better by programs and other things.
so yah =\
Thanks,
MysticGolem