I have problems while trying to play games like SUPER TUX 2 and many more (if not all). The image flicks a lot...

antreas@antreas-desktop:~$ fglrxinfo
display: :0.0 screen: 0
OpenGL vendor string: ATI Technologies Inc.
OpenGL renderer string: ATI RADEON X800 XL
OpenGL version string: 2.1.7412 Release

Can you help me...?