A customized Windows 8 start screen. (Click for larger view.)

Posting from Anaheim: Microsoft isn’t kidding when it says Windows 8 will be the biggest overhaul of its flagship operating system since the landmark Windows 95 release. Application tiles will replace icons, touch-oriented gestures will control major elements of the experience, and users will be able to summon up a menu of “charms” to help them along the way.

This is like no Windows we’ve seen before. And it will take people a bit of time to adjust to it when they first start using it.

That much is clear after experiencing a full day of Windows 8 demos and spending several hours last night using a test build of the new operating system on a touch-screen tablet computer on loan from the company. The sneak peek came in advance of the public Windows 8 preview getting underway right now at the company’s Build developer conference here in Anaheim this morning.

Microsoft’s new approach will be controversial among some Windows traditionalists, and jarring for some everyday users. But if people can get over the initial shock — and adapt to a completely new way of using their PCs — they’ll find a lot to like in what the company has done.

Yes, this is Microsoft’s response to Apple’s iPad, but that’s only part of what’s happening. The changes aren’t just for tablets. They’re for all Windows machines, including laptops with touchpads, and desktops with keyboards and mice. Windows 8 is a wholesale reinvention of a product at the center of the digital lives of hundreds of millions of people.

In short, this is Microsoft’s attempt to keep Windows relevant in the era of mobile devices and the web.

A Windows 8 lock screen. (Click for larger view.)

The differences start at the very beginning.

After turning on a Windows 8 machine, users won’t be greeted with the traditional Windows logon dialog. Instead they’ll see a lock screen similar to the experience on a mobile device, with a customizable picture and “status badges” showing how many messages are waiting for them, the status of their wireless connection, and other notifications from apps of their choosing.

In addition to traditional alphanumeric passwords, Microsoft will offer the option of using a “picture password” — letting people initially use a finger to set up a secret pattern on an image, then repeat the gestures to log in.

Then comes the most radical change: the new Start screen.

This is the hub of Windows 8, replacing the traditional desktop and icons with a horizontal strip of customizable tiles that serve not only as mechanisms for launching applications but also as animated windows into the contents of the apps. The tile for the weather app shows the latest conditions in a particular city. The tile for the email app excerpts the latest message, the calendar tile shows the next appointment, and so on. Developers of third-party apps will be able to offer the same functionality.

Internet Explorer 10 in Windows 8. Web pages will fill the entire screen, but users can swipe from the top or bottom to bring up commands and open pages. (Click for larger view.)

Particularly when those apps are connected to online services, the new approach makes Windows 8 feel personalized and dynamic.

“You can create this mashup of all the things you love, alive in this one screen that brings it all together,” said Microsoft’s Jensen Harris, demonstrating the new approach yesterday. “That’s the magic of the Start screen.”

Panning back and forth on the Start screen is indeed “fast and fluid,” which is apparently the mantra for Windows 8, based on the number of times Microsoft executives repeated the phrase during media briefings yesterday.

But what if you want to search for a file, connect to a printer, set up a wireless connection, switch among applications, or complete any one of the countless other ordinary functions of an operating system?

That’s where you encounter the first big adjustment Windows 8 users will need to make. It’s an entirely new way of interacting with Windows — working literally at the edges of the screen.

Place a finger or mouse at the right edge of the screen, swipe inward, and up comes a sidebar consisting of five icons — for searching the computer, sharing content, connecting to devices, adjusting settings, or returning to the Start screen. Microsoft calls these commands the “charms.”

Swiping in from the top or bottom edge of the computer, from inside an application, will bring up customized commands related to the particular app, replacing the current menus at the the top of the windows. This is because the new type of Windows 8 apps — in a style dubbed “Metro” — will be designed to fill the screen with content, letting users bring up commands only when they need them.

Windows 8 users will be able to switch among apps by swiping from the left edge of the screen, pulling open programs into active view. (Click for larger view.)

Dragging a finger in from the left edge of the screen is the mechanism for switching among open apps. It feels like grabbing an app from just outside the border of the screen and flicking it into an active view. By pausing instead of flicking, it’s possible to position the app you’ve grabbed on just a portion of the screen, next to another running app.

The old-school alt-tab shortcut will also work for switching among apps on machines with keyboards.

It’s important to note that the traditional Windows desktop isn’t going away. Windows 8 will be able to launch the old-school desktop from the new Start menu. And when users open a program that’s written as a traditional Windows app, without the Metro stylings or underlying code, the operating system will automatically shift to the old desktop.

Using Windows 8, it becomes clear why Windows chief Steven Sinofsky said recently that the classic Windows desktop is becoming just another app. The desktop gets its own tile in the Start menu, along with the other apps. When switching among different apps in the Metro interface, the desktop comes up as part of the queue, in addition to any traditional apps running in the classic Windows interface.

The new Windows 8 task manager. (Click for larger view.)

More details from the demos yesterday …

  • Windows 8 isn’t just about Microsoft coming out with a touch-oriented interface. Under the hood, Microsoft says it has made further improvements in Windows 8’s performance, including the way it uses memory, to make machines run faster without boosting the system requirements beyond those for the current Windows 7 operating system. Microsoft also is introducing a new “fast startup” mode.
  • Windows Live SkyDrive will work closely with applications in Windows 8 for storing and synchronizing files online.
  • A new Windows Task Manager will provide a far more detailed view of the underlying processes running on a computer, to help users diagnosing problematic apps. And a new approach to wireless connections will help users switch seamlessly between wifi and mobile broadband networks, while warning them when they’re about to download a huge file over a metered connection.
  • At the Build conference today, Microsoft will demonstrate new ways for developers to write Metro apps, in languages including the web-friendly HTML and JavaScript languages, using familiar tools such as Microsoft’s Visual Studio development application.
  • Microsoft will offer an app store in Windows 8 as the exclusive distribution channel for first- and third-party Metro apps, but it’s not going into detail this week about the financial terms or other information related to its plans. It’s known simply as the Windows Store. (Microsoft is contesting Apple’s claim to the “app store” trademark.)

Timing remains a question mark. Microsoft still isn’t saying when Windows 8 will be released. But it’s widely expected sometime in 2012.

Stay tuned for more from Anaheim throughout the week. Microsoft holds its annual meeting with financial analysts here tomorrow.

Update: More coverage from Build …

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