It looks obvious

A Microsoft-commissioned study that looks at the economic impact of Windows Vista in the United States in its first year of shipment estimates that for every dollar of Microsoft revenue from the new operating system, the ecosystem around it will reap $18 in revenues.

…

The IDC study also says it expects Vista-related employment to reach 18 percent of IT employment in the United States in its first year of shipment, with the 200,000 IT companies that produce, sell, or distribute products or services running on Vista expected to employ over 660,000 people, with another 1.15 million employed at firms that use IT.

While much of this will merely shift from Windows XP-related employment, the report notes that some 60 percent of the growth in Windows-related employment will be driven by Windows Vista.

"These direct benefits—157,000 new jobs and $70 billion in revenues to companies in the U.S. IT industry—will help local economies grow, improve the labor force, and support the formation of new companies," the report says.