i see that too on my netbook
i set the power parameters to turn off screen after 5 minutes in the battery icon near the clock on the taskbar, you can find many profiles and options there that can be edited or selected
i have some problems with hibernation and keyboard not waking up so i disabled that option, you must test it to see if it helps you or not
my system is not doing cpu stepping, i haven't done any test to see if it helps or not or if it is possible, since this is a atom i don't know if that helps to battery life, a atom is really effective running fast and saving power
i only see around 30 minutes lost compared to xp on battery and i think it is the wireless card on xp i have disabled but not on linux, i have to do more tests, lately all i use on the netbook is ethernet adapter and headphones to surf web and watch some videos and listen some music