Those notebooks already have a piss-poor HSF, to keep it from being huge and noisy, and are pretty much at their limits at stock. I wouldnt bother ocing CPUs on notebooks unless you can put a higher CFM fan on the CPU. Was able to do this on the Inspiron XPS and squeezed an addition 300mhz out of it.
<i><font color=red>Only an overclocker can make a computer into a convectional oven.</i></font color=red>