an interesting article from Infoweek which has the following nuggets of information relating to the power savings of Vista.
1. Windows Vista can reduce electricity costs. Businesses can save up to $11 per system, per year by switching to Windows Vista, due to the default power management settings. For a company with 5000 users, this means up to $47,000 of bottom line dollars can be saved annually.
2. The Vista Sleep state is more reliable than XP. Computers resume from Sleep in two seconds, which is about the same time it takes a screen to resume from Idle mode in Windows XP.
3. Power consumption reduction translates into direct CO2 savings. Carbon dioxide emissions are reduced by up to 67 kg of carbon dioxide per desktop PC, per year. For a company with 5000 users, this is 288 tonnes of carbon dioxide emissions reduced.
4. Aero graphics have no effect on overall power consumption. Organizations should take advantage of Aero since it does not have a significant impact on electricity usage.
Source: technet blog