Vein, who was appointed as San Francisco's first CIO two years ago, hopes that the green computing push will also help him achieve his wider IT goals. He is moving to consolidate data centers, standardize technologies and increase the use of virtualization and online services -- no easy task in a government with a history of departmental independence when it comes to IT.

At some organizations, the motivations for moving to greener systems are still grounded in the need to solve data center problems, not driven by environmental factors or marketing considerations. For instance, Denis Muras, a systems administrator at a medical facility that he asked not be identified, said his employer is installing blade servers and retiring older, less energy-efficient systems based on HP's discontinued Alpha processor.

Although the new servers are expected to generate savings on energy costs, Muras said the upgrades are being driven by a need to fit more computing capacity into a data center that's short on available space.

Moreover, using technologies that can increase the energy efficiency of systems isn't always feasible.

Jim Gordon, a senior network engineer at Computer Marketing Group, which resells systems and manages them for customers, said that some of the company's clients would like to reduce their energy costs by using centralized power management capabilities to put their PCs into sleep mode during off-hours.

But, Gordon added, there's a problem: When systems running Windows XP "go to sleep, they don't always wake up" automatically. That can be a problem when IT workers try to apply software updates in the overnight hours, he said.

Despite such hurdles, Bob Carson, an IT manager at Reynolds Electric, an electrical contractor and IT services firm, said he has seen a change in attitude toward energy efficiency among his IT customers over the past year.

At first, "a lot of my clients saw the green thing as an irritation," Carson said. But now they're measuring the energy consumption of systems as well as their total IT power costs, and using the data as a tool for selling business managers on the merits of new IT approaches and investments in energy-saving technologies. "Now," Carson said, "it's not just my [IT] budget, it's our budget."

Meanwhile, Enterprise isn't just touting its green computing exploits to the general public. The committee that's evaluating the environmental impact of new technologies includes a representative from the human resources department. Miller said the company has found that green computing is a strong selling point in attracting IT job prospects, and it wants HR to know what it's doing in that area.