Unfortunately, I overlooked that link in the first post, whoops! Probably something to do with blue link colors on a blue background.
Here's one important thing to realize: Xorg and XFree86 are 2 different implementaions of the X Window System:
You're using XFree86 (since your configuration file is named XF86Config-4), and there's no need to change that. However, using lines of code from xorg configuration files is not necessarily going to work.
In any case, the Modeline statement you added only refers to 800x600, and if I understand right you want 1024x768 (if not 1280x1024?).
Here's what I would do:
1) Remove the offending Modeline command from XF86Config-4. According to the link I provide below, this kind of manual tuning is no longer necessary.
2) Gather information about your new monitor. Most important are the horizontal sync rate and vertical refresh rate. These are given in ranges (see my example above). If you can't find a label on your monitor with the information, which you should, you can go to the manufacturer's website and find a specification sheet.
2) Try using xvidtune to get the necessary information, here is some help:
XFree86 in general:
same document, direct link to xvidtune (read carefully):
More help with XFree86:
You might also still ask for help answering the quesitons that come when using an X configuration tool.
See also here:
Hope that helps.