The Catalyst drivers available on ATI's website are, by default, for desktop cards only. They can
work on Mobility (laptop) systems, but they need to be tweaked slightly to do so (mainly just update some .inf files with the proper hardware names). You can do this yourself using the mobility modder over at driverheaven.net
, or you can grab an already modified copy from omegadrivers.net
. Other people provide customized mods, but Omegadrivers is the most popular.
Hope this helps.