When you run the RedHat program to set up the display, do you choose "Generic Laptop 1024x768" (or something similar)? Or did you try to set your own refresh rate? I would suggest trying to pick a "generic" laptop or LCD at 1024x768. The RedHat configuration program should work. Something you might want to try is selecting the generic VESA driver instead of i810 and see if that works.
The other option is to run the "xf86config" setup program. A step-by-step walk through of that program is here: http://www.bitbenderforums.com/vb22/...?postid=313121
It is for Slackware, but the same thing should work in RedHat. When it asks you for refresh rate, choose 31.5-57 for hsync and 50-70 for vsync. When it asks for video card driver, you can try i810 and if that doesn't work, you can try the generic VESA driver. Set the video ram, resolutions, and default color depth as described in the link above.
Make sure you back up XF86Config before doing anything!
If your display is totally messed up after changing things and you can't see anything on screen: ctrl+alt+F1 will bring you to a text prompt in runlevel 1, you can then go back to where you were before changing anything with "mv /etc/X11/XF86Config.backup /etc/X11/XF86Config" After that, go back to the graphical display with ctrl+alt+F5 or ctrl+alt+F7 (I forget if it is runlevel 5 or 7), then restart Xfree86 with ctrl+alt+backspace.