Battery life of OSX86 and Brightness Change?

[HD!]

On my Intel laptop I have Leopard installed and the battery life in my old Vista HP default was absolutely terrible. On battery, in the lowest brightness setting, it only lastest for one and a half hours. It was only 30 mins on the highest brightness setting.

 

Does Leopard promise me a longer battery life unplugged without having to sore my eyes with the lowest brightness? If it does, is it due to Apple doing a good job with the OS' handling of processes to the amount of battery power required to run the system?

 

Also can we change the brightness setting in our hackintosh laptop and like Windows' Power Options, can the brightness change automatically from when we disconnect the power lead from it? If so then please tell me how, I haven't got Leopard yet but I want to knmow if it's possible.

 

Thanks guys.