On Monday, Microsoft takes its next big step on the road to what is without question the most significant overhaul of its mobile platform in years. is so different from Windows Mobile as to be unrecognizable. After spending a few days with an early prototype phone running the technical preview software, I can say that's a pretty good thing.

Microsoft launched the Windows Phone 7 "hub" concept in February, when we . It's not just the interface metaphor, but clearly at the heart of what Microsoft is doing with the Windows Phone 7 platform. This is Microsoft's first handheld mobile device (the hardware I'm using comes from Samsung, ) to effectively act as a hub for all your digital activities.

The beta software clearly isn't done and not everything worked as expected or really as it probably should, but there's a lot to like and dig into here. Chief among the core benefits found in the Windows Phone 7 platform is its ability to extend to your desktop, your contacts, social networks, your music collection, your games and more. Microsoft took pains to tell me that the slab Samsung phone they handed me for the technical preview, called "Taylor," is thicker and heavier than the final products we'll see this fall and this hardware will never see the light of day as a Windows Phone 7 consumer product. With that in mind, I'm not going to spend time critiquing the actual phone hardware.

Windows Phone 7 seeks to step away the barriers between you and you information, almost from the very first click. One of the very first screens you'll see on startup is one asking you to sign in with a Windows Live ID. This connects your phone with your Windows Live and/or Hotmail e-mail account, calendaring, cloud storage, your Zune account, your Xbox Live gamertag and more. For now, many of the Windows Live benefits can only be realized if you're using the services. Most of these services are still in beta, but should all be live by the time Windows Phone 7 ships.

Once I was through the setup, I had my hub screen, which at first glance looks like it has just seven boxes. In fact, there are up to eleven of these "live tiles", and each gets more useful as you add personal information and connect accounts. Because I connected my Windows Live account, all of my Hotmail contacts instantly synced with the phone, as soon as I added a SIM card. (The phone is on the T-Mobile network, which generally gave me an average EDGE connection).

Included in the eleven tiles are "Phone," "People," "Messaging," Mail," "Calendar," "Internet Explorer," "Games," "Pictures," "Music and Videos," "Marketplace," and Me. You can add to the tiles by pinning things and adding additional mail accounts. My Hotmail account ended up as its own tile/hub, although I would have preferred that it sat in with the other e-mail accounts I set up.

Navigating the interface

Windows Phone 7's interface rolls up and down, and, where appropriate, left to right. Beside the tiles is a full list of apps. I simply swept the main screen to the left and the app list appeared.

At any time I could hit the hardware "Windows" icon button to return to the home hub screen. Beside that button was a hardware "back" button to use if I simply wanted to step back through the screens I had previously viewed. To wake up and then put the phone to sleep, I pressed a hardware button on the side of the phone. Oddly, pressing the Windows button produced no response from the phone when it was in sleep mode; I assume that hardware manufacturers can adjust some of these responses on the final phones.

The phone also borrows a bit from Android phones, including a dedicated search button next to the Windows button. Press it, and you get instant access to Microsoft's Bing search. The app organizes its results into panels: "News," "Web," plus "Local" results. The last category automatically brings up a map with pushpins (which look nothing like pushpins), indicating the location of your local best result. You can zoom in on the map, right down to street level view, if it's available. What was missing was a panel or two for results that fit content found on the Windows Phone: for example, when I searched for "Linda," my wife's contact info did not pop up. The reviewers guide promises this feature; there should be an "All" results panel, but it was missing from my phone.

Voice search is also supported. While it didn't work initially, a hard reboot brought it back to life. The results are effective, though the animation of garbled up letters as it resolves your search is ridiculous and made me think the phone didn't know what it was doing, even though it did.

The apps list includes basic phone features like the calculator, alarm, integrated calendar, mail, maps and more. Like the home screen, the list is longer than the screen, so you can sweep up to see more.