Strange, I swear I did an entire paper in college on the topic of "differences between processors" and I kept running into example where Celerons where made too be more energy effecient then Pentiuams, while the Durons are AMD's equivlent too the Celeron. I would have too look up the data, but both Celerons and Durons with their motherBoards, both only consumed on average of 60% of the power that a Pentium or AMD processor. Maybe my data was faulty, but I swear I did a good job on the research.
As for the Vid cards consuming more power, I'm not a real expert when it comes too hefty 3D cards, but I thought that some of these new, powerful cards these days can really suck a lot of volt juice when installed. I've heard a few cards on the market taking up too 50% of the entire computers power consumption. If this is true, I'm just saying Longhorn could make PC's real "Power hogs" for buisness.