SAN FRANCISCO — Microsoft CEO Steve Ballmer can't afford to be wrong about Windows 8.
On Thursday in New York, Microsoft will unveil a dramatic overhaul of its ubiquitous Windows operating system. If it flops, the failure will reinforce perceptions that Microsoft is falling behind competitors such as Apple, Google and Amazon as its stranglehold on personal computers becomes less relevant in an era of smartphones, tablets and other mobile devices.
If Ballmer is right, Windows 8 will prove that the world's largest software maker still has the technological chops and marketing muscle to shape the future of computing.
"This is going to be his defining moment," said technology industry analyst Patrick Moorhead of Moor Insights & Strategy. Ballmer's "legacy will be looked at as what he did or didn't do with Windows 8. If Windows 8 is not a success, a lot of people will be looking for Microsoft to make a change at the CEO level."
Windows 8 is designed to run on PCs and tablet computers, heralding the biggest change to the industry's dominant operating system in at least 17 years. It also marks the first time that Microsoft has made touch-screen control the top priority, though the system can still be switched into the familiar desktop mode that allows for control by keyboard and mouse.
Ballmer sees Windows 8 as the catalyst for a new era at Microsoft. He wants the operating system to ensure the company plays an integral role on all the important screens in people's lives — PCs, smartphones, tablets and televisions.
"We are trying to re-imagine the world from the ground up with Windows 8," Ballmer told The Seattle Times. He declined to be interviewed for this story.
Early reaction has been mixed. Some reviewers like the way the system greets users with a mosaic of tiles displaying applications instead of relying on the desktop icons that served as the welcome mat for years. Critics say it's a confusing jumble that will frustrate users accustomed to the older versions, particularly when they switch to desktop mode and don't see the familiar "start" button and menu.