I was recently given a Compaq Presario 1235. It has a 12.1" monitor and uses these settings:
HorizSync 31.5 - 50.0
Driver is vesa
Display Modes "1024x768" "800x600" "640x480"
These were the defaults set by a Slackware 10 install. If the monitor would run 1152x864 or 1280x1024 it would suit my preferences better, but I don't think it will work.
These settings would be in your /etc/X11/XF86Config(4) file. I only used RedHat for about a month, so that filename might not be correct.
For more information on that particular laptop, including some RedHat specific information, here are 2 links for laptops:
And you should always try Google <Linux>
which will give you even more results for Compaq Presario 1200