glEnable(GL_POINT_SMOOTH) but the points are still square

My text book said that some openGL distributions will still draw square points after this line. It looks like that's my case. Now how can I upgrade my distribution (or version)? I used the following lines: glPointSize(6); // Points are n pixels in diameter glEnable(GL_POINT_SMOOTH); glHint(GL_POINT_SMOOTH_HINT, GL_NICEST); glEnable(GL_BLEND); glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA); glBegin(GL_POINTS); glVertex2f( 1.0, 1.0 ); glVertex2f( 2.0, 1.0 ); glVertex2f( 2.0, 2.0 ); glEnd();