With Apple bringing a few user interface elements found in its iOS mobile operating system to its upcoming OS X Lion desktop operating system, Microsoft is taking a similar tack for its Windows 8 OS. Previewed last week at the D9 Conference, the next generation of the Windows operating system borrows heavily from Windows Phone 7 by replacing the traditional Windows Start menu with a tile-based Start screen that provides a customizable, scalable full-screen view of apps on the system.

As with Windows Phone 7, the live tiles can display up to the minute information, such as the current temperature or number of unread messages in your inbox, while remaining in the background. Users can also multitask by having two applications on screen at once. With a swipe of a finger, running apps can be "snapped" into place alongside other apps and can be re-sized as desired to let your Twitter feed sit in a column alongside an Excel spreadsheet, for example.

The OS will come with a new version of Internet Explorer 10, while developers will be able to create full-screen, touch-optimized Windows 8 apps using HTML5 and Javascript that can be integrated easily into the Windows UI. Apps will also be available via a new app store.

In addition to a standard onscreen keyboard, Microsoft has also developed a thumbs layout keyboard that splits the keyboard in two and places the two halves on opposite sides of the display. This allows tablet PC users to type with their thumbs while they hold the device in both hands as opposed to having to hold the device in one hand and type with the other as is generally the case with standard onscreen keyboards.

The new touch-optimized interface reflects the fact that Microsoft has designed Windows 8 to be used on a range of devices, from touch-only mobile tablet devices, to touch-enabled laptops and desktops, up to large screen PCs controlled with the traditional keyboard and mouse. While Windows 8 apps will be optimized for touch, Microsoft says the new OS will maintain compatibility with existing Windows 7 software and peripherals.

This one-size-fits-all approach is fundamentally different to that of Apple who, although its iOS and upcoming OS X Lion operating systems will feature similarities, will continue to keep the two as separate entities.

Some, like Daring Fireball's John Gruber, have already criticized Microsoft's approach to create a touch interface on top of Windows to maintain backwards compatibility with its existing software as trying to do too much and, as a result, compromising the effectiveness of the OS. Citing Apple's iWork apps as a prime example, Gruber points out that the iOS iWork apps aren't simply touch friendly versions of iWork apps on the Mac, but are designed from the ground up for touchscreen use.

This also highlights another major difference between Apple and Microsoft. Apple has repeatedly shown it is willing to shed its past, as it did with the introduction of Mac OS X in 2001, which was incompatible with the company's existing hardware and software at the time and the switch from Motorola to Intel processors.

Of course, Microsoft faces a more difficult task in this respect as it has a much larger user base and would face a much bigger backlash if it were to ditch compatibility with legacy apps - particularly from enterprise users. However, Windows 8 seems to offer very little to organizations so most will probably end up skipping it anyway as many did with Vista.

There's no doubt Microsoft had to do something to address the success of Apple's iPad, which has served as a gateway for many consumers who previously would never have considered buying a Mac. Windows 8 definitely looks to have some nice features and Microsoft has obviously put a lot of time and effort into it, but whether Windows 8 is enough to stop the bleeding and even win back old Windows users remains to be seen.

Microsoft is yet to announce a release date for its new OS or even its official name - Windows 8 is just the codename for now.