bus speed makes a difference when:
Pushing huge-ass textures to graphics memory from main memory. Bump mapping and cube mapping increase this. old-ass games like Quake1,2,3 do not.
Performing T+L with the GPU requires all the verticies to be pushed to the GPU which eats up bus bandwidth. Again, old-ass games like Quake 1,2,3 do not.
Bus limitations will be a problem only if and when you can run new games which use such features on your old-ass A1/Pegasos hardware. Bump mapping and T+L have been around for ages BTW, but there is a long game lag for some reason.
