Same problems here, I'm using a HP 6540b with a mobility RADEON 4500.
With the opensource-driver the fan was always running, /proc/acpi/thermal_zone/ shows over 70 degrees, battery is emptying very shortly, xfce-powermanager is unable to change display brightness using [FN + F9/F10].
After installing the propr. ATI driver (fglrx), temprature is reducing to about 55 degrees, fan is running very slow, battery is running much longer, and xfce-powermanager is able to change the display brightness.
Same problems here, I'm using a HP 6540b with a mobility RADEON 4500. thermal_ zone/ shows over 70 degrees, battery is emptying very shortly, xfce-powermanager is unable to change display brightness using [FN + F9/F10].
With the opensource-driver the fan was always running, /proc/acpi/
After installing the propr. ATI driver (fglrx), temprature is reducing to about 55 degrees, fan is running very slow, battery is running much longer, and xfce-powermanager is able to change the display brightness.