I finally completed my beach scene; unfortunately, I found that when I used anti-aliasing, the texture for my terrain (a texture map of sand) didn't show the graininess I wanted; rather, it became blurred.  Is there a way so that the anti-aliasing won't affect the texture map?

Try checking the different boxes for sampling in your shader (it reads something like gaussian, summed area, etc I think). It may help.

Increasing object accuracy to .5 in the render options will give you the best texture map rendering. Also, make sure that Guassian is not selected as a the map interpolation option. Usually, Sampling with the Interpolated selected will work better.