Re: 7600GT won't do 1440x900 with AL1916W?
i had the same issue (same monitor) and it was fixed with these two lines:
you dont need modelines at all to get this working. remove those and under the screen section, just put in "1400x900" under the 24 bit section and you should be ok.
add them under the device section of the xorg.conf
Option "ModeValidation" "NoDFPNativeResolutionCheck"