My 24-in wide-screen is 1920 X 1200 native.
If you are using a wide-screen monitor, be sure to make this entry under the [display] in your FSX.cfg, not required for FS9 IIRC.
[Display]
RUNWAY_LIGHTS_SURFACE_SCALAR=0.4
RUNWAY_LIGHTS_VASI_SCALAR=0.5
RUNWAY_LIGHTS_APPROACH_SCALAR=0.5
RUNWAY_LIGHTS_STROBE_SCALAR=0.7
ChangeTime=4.000000
TransitionTime=4.000000
ActiveWindowTitleTextColor=255,255,255
ActiveWindowTitleBackGroundColor=0,28,140,64
NonActiveWindowTitleTextColor=255,255,255
NonActiveWindowTitleBackGroundColor=24,33,87,64
InfoUpperRightTextColor=255,0,0
InfoUpperRightBackGroundColor=0,0,0,0
InfoLowerLeftTextColor=250,250,250
InfoLowerLeftBackGroundColor=255,251,251,251
InfoLowerRightTextColor=255,255,255
InfoLowerRightBackGroundColor=255,241,241,246
InfoBrakesEnable=True
InfoParkingBrakesEnable=True
InfoPauseEnable=True
InfoSlewEnable=True
InfoStallEnable=True
InfoOverspeedEnable=True
BLOOM_EFFECTS=0
SKINNED_ANIMATIONS=1
TEXTURE_BANDWIDTH_MULT=130
UPPER_FRAMERATE_LIMIT=29
WideViewAspect=True