AS popsUlfr have been saying, the problem is in the drivers. Unfortunly, drivers for laptops are often quite crappy and it can be a bit of pain to get it right.
For your HD2600 Mobility, you want to check A.1.4 here:
http://frictionalgames.com/forum/thread-3754.html
By doing this, you should be able to get the latest drivers to work. I have a HD 2600, so it should work if you get the proper drivers installed.
Regarding X800Pro:
There is a patch in the works for this. First make sure to have the latest drivers installed, then download the demo and add this fix:
http://frictionalgames.com/forum/thread-...age-1.html
That way you can make sure that it should work, once the patch is released.
And the reason why other games work is because they use D3D. Amnesia use OpenGL, which often a lot worse driver support.