ATI Graphics Driver

I have an Inspiron 580S running Windows 7 and AMD Radeon 5450 (1GB). I got the computer 4 months ago, and from day 1 whenever i'd start it up I'd get the message:

THE CATALYST CONTROL CENTER IS NOT SUPPORTED BY THE DRIVER VERSION OF YOUR ENABLED GRAPHICS ADAPTER.  PLEASE UPDATE YOUR ATI GRAPHICS DRIVER OR ENABLE YOUR ATI ADAPTER USING THE DISPLAYS MANAGER. 

When I try to open the ATI Catalyst Control Center I get:

ATI CATALYST CONTROL CENTER CANNOT BE STARTED BECAUSE THE CURRENTLY ACTIVE GPU IS NOT SUPPORTED.

I have downloaded driver updates from the Dell website, powered off, powered on, and still have the same messages pop up.  Can someone please tell me what these error messages mean?  I, CLEARLY, am not computer-savvy.  I have no idea how to open the "displays manager" to "enable" whatever it is I'm supposed to enable, or even where to look for a "displays manager".  If someone can please explain, in simple terms, please, how I can get these messages to stop, and the computer to function properly like it should have been from day one, I would appreciate it.