I am a Vista 64 user and here is the portion of my Terrain Section in my FS9 Configuration file. The "TERRAIN_MAX_VERTEX_LEVEL=21" line is at "21" because I use FSGenesis mesh. If you do not use a 3rd part mesh at all, try 21, 20, and 19 to see which works best for you.
TEXTURE_BANDWIDTH_MULT=400 <----- Try "400". If this creates stutters, try "300" or something along there.
[TERRAIN]
TERRAIN_ERROR_FACTOR=100.000000
TERRAIN_MIN_DEM_AREA=10.000000
TERRAIN_MAX_DEM_AREA=100.000000
TERRAIN_MAX_VERTEX_LEVEL=21
TERRAIN_TEXTURE_SIZE_EXP=8
TERRAIN_AUTOGEN_DENSITY=5
TERRAIN_USE_GRADIENT_MAP=1
TERRAIN_EXTENDED_TEXTURES=1
TERRAIN_DEFAULT_RADIUS=9.500000 <----------- These two lines seem to affect blurries the most.
TERRAIN_EXTENDED_RADIUS=9.500000 <-----------
TERRAIN_EXTENDED_LEVELS=232
Hope this helps!