I'm going to get a new PowerBook 15". I plan to order it with 1GB in one slot so that later I may add another 1GB in the second slot. The question is how much power does each 1GB stick of RAM consume? Is it significant enough to raise the heat load and increase power usage such that one would get noticeably less battery life? A portion of the question might even be if one had more RAM would the increase in system efficiency (less hard disk access for paging) result in improved power usage. I ask because with my PowerBook Pismo there is a noticeable difference in power consumption between having one 512MB RAM card vs two 512MB RAM cards installed.