ATI Radeon HD 4870 driver help

[mknarr]

Hello,

I am currently running:
-Ubuntu 8.04
-AMD Phenom 9200+
-6GB DDR2(1066) PC8500
-M3A32-MVP Deluxe(Wi-Fi version)
-ATI Radeon HD 4870

I was trying to follow a few guides such as:
http://ubuntuforums.org/showthread.php?t=878709

But... Every time I go to install the drivers in the terminal I get the message "can't open ati-driver-installer-8-11-x86.x86_64.run". Since I'm really new to Ubuntu I'm not really sure on what to do, to install it a different way or what?

Some help would be most appreciated. Thanks

[mknarr]

I got the .run to work with the ati control center but it still is saying there is no driver installed or it isn't functioning correctly.