Ok so you install the fglrx rpm. And does it compile correctly? usually I have to force the rpm to install because it conflicts with X libs. After the install it is sometimes necessary to manually build the drivers.
cd /lib/modules/fglrx/build_mod (I could be wrong about the _mod part)
This will install the fglrx.ko module into your modules dir for your current kernel. Now Keep in mind - all of this will work ONLY if you have the kernel source installed. If you dont have the source installed then the module cannot be built, even if you werent building the module you should have the source
Ok after the module is installed run fglrxconfig and setup the machine - tell it NOT to use the external agpgart. Then everything should be golden.