This might be a pretty easy fix but I'm not sure what I'm doing wrong. When I run my 3D code from a box with an NVidia GForce card the lighting looks nice. When I load the same code from an ATI card the lighting looks horrible and over lit like the attenuation was jacked with.
I noticed that OpenGL driver have artifacts on ATI video card, but on NVidia it as fast as DirectX and shines as DirectX. So i suggest you to try Direct3D9 renderer if you using OpenGL.
Interestingly enough, when I switch to D3D9 I get the opposite effect. Instead of over lit it's under lit, like almost completely black on any mesh that has lighting enabled.