If you use a current Fedora release, you can only use the Radeon drivers which are used by default. Maybe you can get a small performance boost if you use the drivers from the rawhide repo.
If you want to try the newer drivers, do this:
yum update --enablerepo=rawhide kernel libdrm mesa-dri-drivers mesa-libGL mesa-libGLU xorg-x11-drv-ati
The packages from the rawhide repo are usually for testing purpose though.
Catalyst 9.3 (Link)
is the newest Linux driver you could use on a Linux distro. Fedora 14, F13, F12, Ubuntu 10 or 9 will like most newer Linux distro versions not work with this old Catalyst driver. CentOS 5.5 or Fedora 11 would probably work with Catalyst 9.3. I'm not sure if this driver would be considerable faster than the Radeon driver.