Microsoft has officially announced the five versions of Windows 7 it will sell at launch, together with a version specifically designed for low-cost netbooks.

Microsoft has officially announced the five versions of Windows 7 it will sell at launch within the United States, together with a version specifically designed for low-cost netbooks.

The five versions available for U.S. customers will be: Windows 7 Starter, Windows 7 Home Premium, Windows 7 Professional, Windows 7 Enterprise and Windows 7 Ultimate. But Microsoft will only sell Windows 7 Home Premium and Windows 7 Professional at retail, in a bid to eliminate some of the confusion caused by a plethora of Windows Vista versions.

A sixth version, Windows 7 Home Basic, will only be sold in emerging markets, Microsoft said.

Want all the details that we know about the new Windows 7 versions? Check out our FAQ: "The Windows 7 Versions: What You Need to Know"

Microsoft did not release the prices of the new Windows 7 versions, and offered no additional details as to when they would launch. Most expect Windows 7 to ship near the end of 2009, however. Microsoft also declined to say when it would stop selling Windows Vista.

"We've learned a lot over the years as we've released versions of Windows to the market. We spent a lot of time listening to customer and partner feedback," Microsoft said in a document describing the changes that was released to PCMag. "We heard from customers that they liked the choices Windows Vista offered, but that upgrading sometimes meant tradeoffs. Customers told us that they want us to make it simpler to identify which version is right for them."

And that means that a single version  Home Premium  will be offered to consumers, with a separate version  Professional  offered to businesses. Both the Home Premium and Professional SKUs will contain discrete features that aren't overlapped to the other.

So why not leave it at that? "When you have a customer base of more than one billion, two options can't satisfy all of their varied needs," Microsoft explained. "For that reason we will continue to offer a few targeted SKUs for customers with specialized needs."

Windows 7 Ultimate Edition, meanwhile, won't be sold directly to consumers. Instead, Windows 7 Ultimate will be an upgrade offered only as an add-on, which also means that consumers will be forced to pay for Windows 7 Home Premium or Windows 7 Professional, and then pay again for the upgrade. However, Microsoft will roll out all of the versions on a single disc, allowing users the choice of either buying offline media or applying for an online upgrade key that will unlock the additional capabilities.

"Ultimate combines all of the features of Windows 7 Home Premium plus provides access to all of the Enterprise features including BitLocker, BitLocker To Go, AppLocker, BranchCache, DirectAccess (accessing a corporate network without Remote Access Server installed), MUI, etc.," Microsoft said. BitLocker and AppLocker lock down data and applications, respectively.

And Ultimate Extras? Gone. "Our new approach to planning and building Windows doesn't have the capacity to continue to deliver features outside the regular release cycle," Microsoft said.

Perhaps the largest change, however, is Microsoft's recognition of the netbook market. Previously, Microsoft sold its Starter software only into emerging markets. Now, the company has positioned Starter as an ideal entry point for extending Windows 7 into netbooks. The catch? Like other Starter editions, that netbook will only run three applications at a time, an arbitrary limitation the software imposes. Those limitations ignore background services like antivirus applications, but trigger when the controlling antivirus application is opened, Microsoft's documents say.

Starter is described as a "worldwide entry-level SKU". "Windows Starter has been our entry-level offering in emerging markets with Windows XP and Windows Vista," Microsoft's documents say. "With Windows 7 we are making Windows 7 Starter our worldwide entry-level offering for small notebook PCs (also known as netbooks).

"While these PCs with sufficient hardware will be able to run any Windows 7 SKU and we believe that most consumers will want the rich experience offered by Windows 7 Home Premium or Windows 7 Professional, we recognize that some consumers want a very low price point for their small notebook PC and only have basic computing requirements," Microsoft added. "Windows 7 Starter meets the needs for a certain segment of customers with reduced computing requirements."

One interesting twist: Microsoft claims that any netbook should be able to run essentially any version of its Wndows 7 operating system: "However, Windows 7 was designed in a way that any edition of the OS should be able to run on small notebook PCs with sufficient hardware," the documents say.

That, in part, is because the company said it has "invested significantly in engineering efforts around improving performance, reliability, and compatibility in Windows 7."

On the business front, Microsoft will offer Windows 7 Professional, with the capabilities of joining a managed network, backing up data over the network, and encrypting data. The software will also allow users the option of location-aware printing, such as printing to a home printer while at home, and defaulting to a shared printer in an office environment.

Enterprise will offer a step up for Professional users, and will only be available through volume licensing. With that version, business users will have the option of using BitLocker data encryption on internal and external drives, locking apps with AppLocker, improved remote access without the need for a VPN with DirectAccess, and a decrease in the time to open a shared file with a service called BranchCache. Both of the latter services will require Windows Server 2008 R2, Microsoft says.