Ati graphics card:

• Right click the desktop.
• Select "Properties".
• Select the tab "Settings".
• Click on the "Advanced" button.
• Select the tab "Catalyst Control Center", or similar (look for the Ati-logo).
• Click to open the Control Center.
• In the menu to the left click/expand "3D".
• Select "Anti-Aliasing" in the menu.
• Deselect the "Let the application decide" check box.
• Optionally set the slider to a higher value.
• Click OK.
• You will need to restart the Screensaver for the setting to have effect.