what you mean by changing your xf86config file?
do you know you are doing?
if you don't, don't mess with it.
first of all, you need a driver or a file with rpm extension at
and your xfree86 version was 4.3.0.
first login as root
make a backup of your xfree86config file.
then install the rpm file by "rpm -Uvh --force fglrx-glc22-4.3.0-3.2.8.i586.rpm"
use "fglrxconfig" to creat a new xfree86 file for you and your card should be working after you restart your machine.