I just bought a new NEC 1920NX 19" LCD monitor. While everything seemed to work initially, I cannot get X to run in the monitor's native 1280x1024 resolution. The biggest I can get is 1152x864. the 1920NX is newer than the version of Red Hat 9 that I'm running, so it isn't included in the list of preconfigured monitors, but I can't find a generic 19" LCD setting that supports 1280x1024. When I select the generic 1280x1024 monitor at 60 Hz, it won't allow a higher resolution than 1152x864. I'm running KDE 3.1-11 on the 2.4.20-13.9 kernel. Is there a solution to this problem short of reinstalling Red Hat and hoping that it has this new monitor preinstalled?
Thanks in advance.

Open the XF86Config file with an editor, and look at these lines:
Subsection "Display"
Depth 24
#My default depth, put your resolution at the beginning of this line of resolutions. Modes "1024x768/60Hz" "1024x768" "800x600" "640x480"
ViewPort 0 0
Virtual 0 0
EndSubsection
EndSection

Put 1280x1024/60hz (or whatever refresh rate that's ideal) at the beginning of the section for your default depth.
Restart X to apply the changes. Don't forget to backup your old XF86Config to recover faster in case something goes wrong.

I tried editing the /etc/X11/XF86Config file, adding the "1280x1024/60hz" line at the front of the Modes list, but it did nothing. When X starts up, I'm still in 1152x864, according to the Red Hat display tool.

Did you put it in the section for your default depth?
This section tells which depth is default.
Section "Screen"
Identifier "Screen 1"
Device "video0"
Monitor "monitor0"
DefaultDepth 24