Microsoft CEO Steve Ballmer really wants to sell you on Windows 8, touting features ranging from a new lock screen that still shares updates to the benefits of the controversial Metro user interface.

In a demo and discussion of the new OS at the Dell World conference on Friday, Ballmer focused on four key features, according to a report from Information Week, though some of it was ground that’s already been covered.

A new lock screen that pops up when you’re away from your PC displays a “peaceful mountain view.” And though the OS is locked, you can still see prompts for incoming e-mail messages, social network posts, and other updates so you know what’s waiting for you when you log back into Windows.

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The new Metro-based Start screen has already been demoed and appears in the Windows 8 Developer Preview, but Ballmer took time to once again highlight this new feature. The CEO showed how a user can rearrange the various tiles by dragging and dropping them around the screen. Of course, of all the new features destined for Windows 8, the Metro screen has probably aroused the greatest number of complaints and concerns from Windows users.

In a recent Building Windows 8 blog, Windows Live President Steven Sinofsky admitted that the company has received harsh criticism from people who just don’t like the new Metro UI Start screen. Some have criticized the new screen for not offering the flexibility and organization of the traditional Windows Start menu. Others have griped that the new touch-based Start menu may work fine on smartphones and tablets but has no home on a PC where people still use a keyboard and mouse.

In response, Microsoft reminded people that the Start menu seen in the Developer Preview is by no means the final version. The company said it has been tweaking the feature to address some of the concerns and questions among the user population.

At Dell World, Ballmer also showed the audience how to “extract” specific data from a news feed or stock market report to display such data in a separate tile that’s constantly updated. Microsoft has been touting the ability of the Metro Live Tiles to provide users with the latest information on a range of items without having to leave the Screen screen.

Finally, Ballmer turned his attention to Windows Server 8 by highlighting a live migration feature that will let IT administrators move a virtual machine to a physical server without any interruption to the business. Though that feature first appeared in Windows Server 2008, its implementation in the new server OS is “simpler and smoother,” according to the Information Week report.

Microsoft hasn’t been shy about showing off and discussing Windows 8, at least in the operating sytem’s current state. It released the Developer Preview edition a little more than a month ago at the same time that it demoed the OS at its Build conference.

The company has also been explaining several of the changes and new features in Windows 8 via its Building Windows 8 blog. And it’s invited and responded to feedback from users through that blog, even when that feedback has been less than positive.