Is there ATI specific problem?

Does anyone know if there are any specific operations I should avoid for ATI mobile chips ?

My program is Windows based and use a lot of data and texture.

Here is the FPS
GeForce4GO with Pen4 1.6G -> 60
Mobility Radeon7500 with Pen4 1.6G -> 11
Desktop Intel 815 Onbord with Celelon 1.0G -> 30
Desktop Radeon VE -> worked fine.

I checked the pixel format descriptor and all are using Hardware Acceleration.