Microsoft will release a developer preview of its upcoming Windows 8 operating system tonight, the company announced at its BUILD conference in Anaheim, Calif. today.

Microsoft will release a developer preview of its upcoming Windows 8 operating system tonight, the company announced at its BUILD conference in Anaheim, Calif. today.

The download will be available via the Windows Dev Center at 8pm Pacific time Tuesday night. That includes a 64-bit (x64) build with development tools to build apps and a 32-bit (x86) or 64-bit (x64) build without development tools.

Microsoft has been revealing a few details about Windows 8 here and there via its , including a , a user interface optimized for touch and tablets, and . Today at BUILD, executives took a deeper dive on the new OS, which Windows chief Steven Sinofsky said is a "bold re-imagination" of Windows.

Perhaps trying not to poke the , the Windows 8 store will be known as the Windows Store. It will allow developers to sell their apps anywhere Windows is sold worldwide, from games to productivity tools. Microsoft promised a particularly rich experience ("flicker-free action") for games on Windows 8, thanks to the .

Microsoft again showed off its "Metro" interface, which is a very Windows Phone-esque layout that basically , with a focus on touch. Metro apps for Windows 8 will fill the entire screen so the user isn't distracted, but they will still communicate with one another behind the scenes so you can email photos, for example, from a variety of sources, whether that's the hard drive, Facebook, or Flickr. SkyDrive, meanwhile, will sync all that content across devices in the cloud.

Microsoft said Windows 8 is "the best of Windows 7, only better," meaning the new OS takes its predecessor and boosts performance, security, privacy, and reliability, the company said.

At the Consumer Electronics Show (CES) earlier this year, Microsoft provided a glimpse of a Windows system capable of running on almost any System on a Chip (SoC), including those from Intel, AMD, and ARM-based systems from Qualcomm, Nvidia, and Texas Instruments. Microsoft continued on that theme today, promising "one Windowsmany shapes and sizes." That includes support for ARM-based chipsets, x86 devices, touch, and sensors, so Windows 8 will scale whether it's running on a 10-inch tablet or 27-inch, high-def screen.

Sinofsky did not have any details on when Windows 8 will be released. "We'll be driven by the quality and not the date," he said.

The 5,000 people in attendance at the BUILD conference will get to test out the Windows 8 developer preview on a Samsung tablet optimized for the new tablet, Sinofsky announced.

The Samsung Windows Developer Preview PC is a 11.6-inch tablet with a 1366-by-768 touch display. It runs a second-generation Intel Core i5 processor and comes pre-loaded with the Windows 8 developer preview software. It includes 4GB of RAM and a 64GB SSD, as well as "an array" of sensors, Sinofsky said, and USB, microSD, HDMI, and Pen. An optional dock includes USB, HDMI, and Ethernet access.

3G service will be provided by AT&T; the carrier will provide BUILD attendees with 2GB of free monthly data for one year. Click the image above for more spec details. At this point, it's just a developer device; no details about a consumer release were discussed.

PCMag's Michael Muchmore has already tested out the preview on his Samsung device. For more, see his and the slideshow above.