Ruston Panabaker, Microsoft's principal program manager of strategic silicon partnering, shows how later builds of Windows 7 were able to let the processor enter low-power states for longer periods of time, saving more power.

Upgrading a newer machine from Windows Vista to Windows 7 might mean that you get to see the last few minutes of that DVD on a long flight.

At a demo on Tuesday, Microsoft showed two identical laptops playing the same DVD, with the Windows 7-equipped notebook getting 20 percent better battery life than one running Windows Vista. In general, users can expect newer systems running Windows 7 to offer 10 percent to 20 percent better battery improvement when watching a DVD.

"We're achieving a very significant amount of battery savings," said Microsoft principal program manager Ruston Panabaker.

Microsoft and Intel declined to say just how much overall battery life improvement Windows 7 might offer as compared to Vista, saying there are too many factors that can influence such results.

"I don't want to state a number," Panabaker said at the event, which was organized by Intel and Microsoft.

Microsoft and Intel showed these power consumption improvements results for a system running Windows 7, left, and Vista. The left chart shows consumption while the system was idle; at right, when playing a DVD.

The event was designed to outline the joint work that the two halves of Wintel have been doing to make Windows 7 perform better in areas such as virtualization, power management, and performance.

On the performance side, Microsoft and Intel showed a reference system that can boot up in 11 seconds, although again real-world performance is likely to vary a lot based on what's inside the PC and how well tuned it is. For instance, the system shown Tuesday had a solid-state drive and other high-performance componets.

The move comes as Microsoft gears up for the October 22 launch of Windows 7.

Perhaps the most encouraging thing for Microsoft is the fact that Intel itself is willing to use Windows 7 within its own corporate walls. The chipmaker has been an XP-only shop throughout Vista's life. In an interview here, Intel VP Stephen Smith said that Intel had some internal applications that weren't Vista-compatible and the benefits of moving to Vista didn't justify the costs.

By contrast, Smith said several hundred people inside Intel are already running Windows 7 on their corporate machines.

Playing a DVD, a Windows Vista Ultimate system, left showed an estimated battery life of 4.14 hours, but the Windows 7 Ultimate system on the right showed 5.5 hours.