Following your saga (first post, second post, third post, fourth post) I have a suggestion that can save your time and energy.
The proprietary drivers that you are trying to install are not supported anymore for your hardware and operating system. Yes, there are some trick and tweaks, like downgrading xorg but in the long run it is not worth the trouble. Use open source drivers and do not try to replace them with something else if there is no good reason for it.
Ubuntu should use open source drivers out of the box but you can install them also with this command:
sudo apt-get install xserver-xorg-video-ati xserver-xorg-video-radeon
Just make sure that you remove amd drivers you might have in your system. The amd drivers that come from the standard repository are either fglrx or fglrx-updates. The "purge" command removes the package completely.
$ sudo apt-get purge <package-name>
I struggled a year to get proprietary AMD drivers work on my HD4870 and I don't advice anybody to do the same. If you can't get the performance you need with the open source driver then replace your old amd card with some nvidia card. For and example you could buy it second hand and do background search in the internet beforehand whether it works with Ubuntu.