nVidia drivers and Anti-aliasing

In the display properties for my GeForce 256 under the OpenGL section, there is an option for antialiasing.

I turn it on and nothing appears to happen.

Do I need to restart?

What sort of anti-aliasing does it do? multi-sample or super sample?

Does it actually do anything at all?

Does any body have a good example that will demonstrate it working so I can actually see what it does?