I'd like to set my mpb (early 2009) to "higher performance" for the power adaptor and "better battery life" while on the battery. Can someone confirm if this is possible? I can't seem to do this because when I change it on one power source it automatically changes it on the other power source. Is there something obvious I am missing - I have searched the forums in vain. (I have checked that I don't need any software updates). Thanks for any help on this. Cheers.