After the screws are removed from the top and bottom, you will find that the entire base is still held down by small clips all around the laptop.

The second picture shows the heatsink for the Intel GMA 3000 Graphics chip located on the opposite side of the motherboard to the touchpad. On the top of it is a sticky thermal pad that helps to distribute heat to the base.

That thermal pad on the heatsink has a double function, in that it is stuck to the base and would need a little effort to separate them from each other.