"In many ways, xorg.conf sits on the surface of your
installation like the broken walls of some lost building on an
archaeological site. The file contains the last vestiges of what
was once a complex and convoluted configuration file, using a
syntax and language from a time gone by. Over the years, those old
structures have been removed, rebuilt, subverted, tweaked and
squeezed through several generations of users, distros and
hardware. It has finally got to the point where many modern
distributions (such as Fedora 10) eschew xorg.conf completely,
taking advantage of the automatic configuration hidden within the
newer versions of X.org.
"For most users, this automatic trend is a definite advantage.
It means that those days where nothing appeared on screen after
installation, or when the keyboard didn't type type the right
letters, are long gone. But xorg.conf is still relevant, and
whether you want to fine-tune your setup for extra performance or
troubleshoot a display problem, it's still the first port of call
when the automatic tools aren't quite automatic enough."