you could go out and buy a vantec iceberq and use that to cool the nb and the other small copper heatsink you get in the package could be used to cool the sb
if you don't want to spend any money, take of the nb heatsink, clean up that bubble gum thermal goop asus put on there and replace it with arctic silver 3
you could stop there but if you want to go an extra step, get a 40x40x20 fan and screw it on the nb, it fits very nicely i'm told my many
if you wanted to do some more, you could lap the nb heatsink and lap the nb itself(both the heatsink AND nb are concave for many ppl) but these last 2 things i do no recommend unless you're experienced in lapping....
all i did was clean up the bubble gum and put some as3 on there....