Since the upgrade to 8.10 of Ubuntu from 8.04 I found that the ATI Catalyst Control Centre (ccc) had been removed from the Applications menu.
Looking at Synaptic I saw that there was a package called fglrx-amdcccle already installed. This is the control Centre - it had just been missing from the menu. After a little hunting I determined the Control Centre could be invoked by running the command "amdccle".
To Simplify this a little I created a menu item for the "ccc" by right clicking on the "Applications" menu, selecting "Edit Menus" and then "New Item" - and filling out the details as shown below.
The is the app you need to control external monitors working with the T60p.