Having just resolved heat/fan issues on my 15 in, 1.25 PB I'm very aware of the temperature of the computer. Just yesterday I installed 2 sticks of 512 MB memory, replacing the two 256 MB sticks the book came with. The memory was purchased from Small Dog and appears to be the correct memory (though, surprising to me, the actual sticks were smaller in width--length was the same). The machine is snappier and I'm quite happy with the switch, but it now runs a few degrees hotter. Not really a problem but when I play games the fan comes on early and stays on. It used to come on occasionally, and only for a few minutes. Is this normal behavior? I would think that Small Dog would sell memory that's within specs, but I don't know if adding more memory would up the internal heat. If this is abnormal, I'm returning the memory and trying a different company. If this is to be expected than all is well. I'm currently researching laptop stands and coolpads to buy.