Microsoft is unveiling the official Windows Vista version line up on February 27. While the names of the six core SKUs are familiar, thanks to a recent information leak, some of the specifics regarding the feature list for each variant might catch some company watchers by surprise.

Microsoft is readying six core Vista packages, or SKUs, plus two additional releases customized for the European Union that won't bundle in Windows Media Player, as ordered by European antitrust regulators. The six Windows Vista variants are: Windows Starter 2007; Windows Vista Enterprise; Windows Vista Home Basic, Windows Vista Home Premium, Windows Vista ultimate, and Windows Vista Business.

Also on the list are two additional releases, Windows Vista Home Basic N and Windows Vista Business N. The "N" releases are those which do not include Media Player.

Microsoft currently offers six core Windows XP SKUs: The line up includes XP Home, Professional, Media Center, Tablet PC, and Professional x64, and Windows XP Starter. (Microsoft also offers "N" versions of its XP Home and XP Professional releases, as stipulated by the European antitrust regulators.)

With Vista, there will not be separate Tablet, Media Center or x64 SKUs, said Barry Goffe, director of Windows client product management. All of the planned Vista versions, except Windows Vista Starter, will be available in both 32- and 64-bit flavors. All SKUs will integrate Internet Explorer 7.0, the new Vista desktop search, parental controls and Windows Defender antispyware technology. And all of the Windows Vista business SKUs will embed features designed to appeal to small/mid-size businesses (SMBs), Goffe said, obviating the need for a separate Vista small-business variant.

The new line up is "more focused on how people will use their PCs, rather than around hardware types," Goffe explained.

Windows Vista Starter will be available in developing nations only. Like the current Windows XP Starter products, Vista Starter will be customized for users in particular countries and will include fewer features and functionality. Starter will not be sold at retail; instead it will be available preloaded on cut-rate PCs.

Windows Vista Home Basic is aimed as casual PC users who do little more than surf the Web, check e-mail and create/store/share basic documents, Goffe said. The Home Basic version will not include support for the Aero Glass user-interface effects that will be part of other Vista SKUs.

Windows Vista Home Premium will include the same type of functionality currently delivered by Windows XP Media Center and Windows XP Tablet PC Editions. The Home Premium variant also will include technology support digital photography, movie-making and TV, as well as mobility-focused technologies.

Windows Vista Business will include the full-fledged Aero user interface, as well as Tablet PC functionality built-in. The higher-end Windows Vista Enterprise will include all of the features of Windows Vista Business, plus BitLocker drive encryption; Virtual PC Express virtual-machine support; the Subsystem for Unix-based Applications (SUA), which is designed to allow Unix applications to run on Vista machines; and access to all worldwide languages supported by Vista via a single deployment image.

The catch? Microsoft will make Windows Vista Enterprise available to Enterprise Agreement (EA) and Software Assurance (SA) volume-licensing customers only. Microsoft officials have been seeking ways to entice more users to sign up for Microsoft's volume licenses, and increasingly has been using new product and service incentives as carrots to attract and keep EA and SA customers.

But there's a loophole for Vista customers who are not interested in signing up for volume licenses. That loophole is Windows Vista Ultimate, the SKU which will include all of the features in Vista Home Premium and Vista Enterprise in a single offering.

"Vista Ultimate is for people who have a single PC that they use both at work and at home," Goffe said. "It also will be good for small-business owners and managers who have PCs with customer data stored on them" and who need to insure it stays secure.

Goffe acknowledged that some users interested in Vista Enterprise, but not the volume-licensing stipulation, might choose to opt for Vista Ultimate as a workaround. But Microsoft has no plans to position Ultimate in that way, he said.

It's not clear how much of a premium Microsoft plans to charge Vista Ultimate users – or customers of any other Vista variant -- for that matter. Microsoft will release Vista pricing at a later, unspecified date, Goffe said, some time before the six versions begin shipping in the latter half of 2006.

Even minus the pricing details, the Vista SKU lineup itself is significant, however, Goffe maintained.

"For the first time, there is a good/better/best ranking" for the Windows releases," Goffe said. "There are different levels of features in all the SKUs. Our line up is more rational and more customer-focused," he added.