The combination of free software from the likes of Linux and GNU with virtualisation - which maximises computing efficiency - is a compelling proposition. It offers lower costs, flexibility and greater efficiency, plus environmental benefits

Bogamil Balkansky, chief of product marketing at VMWare, the leading virtualisation vendor, agrees that vitualisation is inherently green. "It helps shrink the physical footprint and the energy footprint," he says. "For every application running virtually, the data centre saves about 7,000 kilowatt-hours a year."