Yes, I think they removed the "Enhance" menu in latest versions of the drivers, it's available only for Antialiasing. But this should simply mean it should always Enhance.
However, from your screen, it really looks like you haven't enabled it, because it's the precise, exact, effect of total lack of Anisotropic filtering. There's a similar setting in FSX graphic settings too: None, Bilinear, Trilinear and Anisotropic. Try Anisotropic, with the nVidia Control Panel at 16x.