Try finding new graphics drivers for your what I assume to be integrated graphics card. Right now it apparently reports to LFS (via DirectX) that it doesn't support antialiasing, hence LFS not displaying the option. Maybe newer GFX drivers enable this option, but I fear that even if they did your GFX chip wouldn't have enough performance to make good use of antiasliasing.
E: Though a quick Google search suggests that your GFX chip doesn't support antiasliasing at all :worried: