On Avsim this morning -
Everyone should install this file. Flight Simulator X terrain is defined in the terrain.cfg file. During testing, we have determined a certain number of modifications to this file that will correct some problems with the FS world and also provide more options for scenery designers. For example, in some places, water bodies display rocky areas - this file fixes that. Please read the detailed explanation that is included, and then install this modified file.
-from Microsoft developers!
Thanks Davec, I've saved the location for when I get FSX.