Are you using the DirectX or OGL plugin, for your card you should be using the OpenGL plugin. DirectX plugin is meh compared to OpenGL, Open looks much nicer and fixes a lot of graphical problems in games that haven't been addressed yet with the DirectX plugin. Also the DirectX plugin doesn't work correctly in the newer revisions and is pending improvement.
Anyway if you are trying to use the OpenGL plugin and having these problems, try downloading updated drivers from Nvidia for your card and updating your video card drivers. Double check your configuration to ensure there are no graphics hack enabled which are not needed for most games.
Anyway if you are trying to use the OpenGL plugin and having these problems, try downloading updated drivers from Nvidia for your card and updating your video card drivers. Double check your configuration to ensure there are no graphics hack enabled which are not needed for most games.