

The first batch of phones running Microsoft's brand-new Windows Phone 7 operating system hit U.S. stores Monday.

More Windows Phone 7 coverage on Gadget Lab:- Samsung's Windows Phone 7 Packs Intuitive, Visual Punch

Windows Phone 7 is now available on three handsets: the HTC HD7, the HTC Surround and the Samsung Focus (pictured above). The HDC7 is available for T-Mobile customers, and the Surround and Focus are available for AT&T customers.

The phones are listed at $200 retail, but some web discounts bring them down to as low as $150 with a new contract.

Two other Windows Phone 7 handsets — Dell's Venue Pro and the LG Quantum — are scheduled to ship during the holiday season, according to Microsoft.

All the phones include a Snapdragon processor, 256 MB of RAM, at least 4 GB of flash storage, 802.11 b/g wireless, a capacitive touchscreen and five sensors (A-GPS, accelerometer, compass, proximity and light).

Full specifications for the five Windows Phone 7 handsets are available at Microsoft's website.

Windows Phone 7 is Microsoft's complete do-over on a mobile OS after scrapping Windows Mobile in late 2008. For more details on what happened behind the scenes, see our feature "How Microsoft hit CTRL+ALT+DEL on Windows Phone."

Photo: Jim Merithew/Wired.com