Ubuntu 7.10 on Dell Inspiron 6400

Hello everyone, I recently received a Dell Inspiron 6400 (the name in Europe, think in the US it's 1505?). Ubuntu 7.10 Gutsy Gibbon runs very good, but I have an issue with the screen brightness. When working on battery the screen brightness dims back to a very low setting when the idle timeout kicks in. This is normal, but moving the mouse or hitting the keyboard does not restore the previous setting. I have to manually use the Fn+(arrow keys) to increase the screen brightness. I tried messing around with the key_constants file that is used by acpi_fakekeys but I don't think the screen brightness is controlled by acpi. Does anyone else have this issue or does anyone have any clue how I can fix it? Btw, I bought the laptop in Belgium so I was unable to buy it preconfigured with Ubuntu. This is a Windows Vista laptop that I fixed by installing Ubuntu ;) I hope Dell starts offering Ubuntu pre-installed in Belgium really soon! Kind regards, Michael