I also tried 640*480 fullscreen mode obtaining the same fps but at first sight the window mode seems faster!
During my experiments I always checked the fps on Amnesia start menu with FRAPS:
11 fps with default medium settings (1024*768)
19 fps with everything at minimum (640*480 window/fullscreen)
If you can play this game with the same graphic card (X2330 is a typo??? Can't find this card with google! 128Mb?), maybe I have some conflict on my pc! No way to format it: I have to move house soon!
Never try Penumbra Games: maybe I can download a demo and give it a try!
No problems with other OPENGL games like Doom 3, Prey, Quake 4 (I know it is the same engine).
Using OpenGL Extension Viewer 3.0 it seems that my card supports 100% 2.1 extensions. This is the ATI Mobility Radeon™ X2300 Specs:
http://www.amd.com/us/products/notebook/...specs.aspx