The battles for energy efficiency aren't just being fought by chipmakers, server and PC vendors, and other hardware companies out there. There's a similar battle heating up on the OS layer between Microsoft and Linux.
Linux appears to have an advantage at the moment: Companies are becoming increasingly open to adopting the platform both in the server room and on the desktop. Big-name vendors like IBM, HP, and Novell are giving the penguin a push in the datacenter, framing it as a flexible and energy-efficient platform. The fact that Linux offers greater virtualization opportunities than Windows (a sentiment recently expressed by the VMWare CTO Mendel Rosenblum) only strengthens the platform's green standing.
http://weblog.infoworld.com/sustainableit/archives/2007/08/linux_and_windo.html?source=rss