You're viewving a non traslucent menu bar in leopard, and you dont' why? Apple explains why it occurs. The problem is because the graphics card is not compatible with Core Image.
"Some graphics cards, such as an NVIDIA GeForce FX 5200, may not have the necessary OpenGL capabilities to display a translucent menu bar even though they are compatible with Core Image. Those cards should render most effects, but not the translucent menu bar."