You get a 200 pin, DDR2 PC2-4200 (which is 533). It may be made by crucial, corsair (I hope corsair). Someone also said Sager laptops have been sent out with apache ram. Who actually makes the ram in the laptop, who knows, but they will all be 200pin, DDR2 PC2-4200.
The ram you get stock is great. Regular DDR2 ram is not much better then DDR performance series ram, but right now for laptops, there is no performance series ram anyway. I would say this is about as good a ram as you can get for laptops right now. No, you would not notice any speed increase by changing, even if there was a faster 200pin stick of ram (PC2-4200 is fastest I have seen for sale right now). As for stability, is your 9860 not running stable?