You should be able to get a new XF86Config-4 if you run
Code:
/usr/X11R6/xf86config
or
Code:
/usr/X11R6/xfree86 -configure
as root. The first option will ask you about your graphics setup and then create the config for you, and the second option will attempt to detect what hardware is in your system, and will create an X configuration in /root/XF86Config-4.new which can then be copied into /etc/X11. Or, if you're desperate, you can make the file by hand--but it is a serious pain!