However, the company is emphasizing two main SKUs (stock-keeping units) of the forthcoming OS -- Windows 7 Home Premium and Windows 7 Professional -- saying these are the ones most customers will buy, according to on Microsoft's Web site.
With Windows 7, Microsoft hopes it will be easier for customers to decide which edition of the OS is right for them. By doing so, the company once again seems to be trying to learn from mistakes it made with the release of Windows Vista, premium versions of which had special hardware requirements that hindered customers' transition from XP and confused users as to which edition they should purchase.
When Microsoft released Vista, premium versions such as Windows Vista Ultimate and Windows Vista Home Premium did not run on many PCs that already were running Windows XP. Microsoft tried to give hardware partners and customers fair warning of this and through a controversial program had OEMs put stickers on new PCs to let customers know which version of Vista those machines could run.
Still, many customers did not feel Vista hardware requirements were communicated effectively and Microsoft is still over that sticker program, called "Windows Vista Capable."
In addition to Home Premium and Professional, Windows 7 will come in the following editions that mirror Vista's SKUs: Windows 7 Starter; Windows 7 Home Basic; Windows 7 Enterprise; and Windows 7 Ultimate.
Microsoft is recommending either Windows 7 Home Premium or Professional for most of its customers, it said.
Windows 7 Home Premium is for the average user and Windows 7 Professional -- replacing Windows Vista Business -- is for small businesses and people who work at home but have to operate in an IT-managed or business environment with security and productivity concerns, the company said.
Windows 7 Starter is a limited-functionality version of the OS that will be available worldwide but only as a pre-install by OEMs (original equipment manufacturers). This expansion of its availability -- Vista Starter was only available in emerging markets -- led one blogger to surmise that Windows 7 Starter is the version Microsoft will push for the netbook market.
"This version will only be sold through PC makers to users," wrote Paul Thurrott on the popular , which has a list of SKUs and the differences in functionality. "This suggests that netbook makers will choose this version, even in the US."
Windows 7 Enterprise is Microsoft's SKU for its enterprise customers, while PC enthusiasts that "want it all," according to Microsoft, should purchase Windows 7 Ultimate.
Like Vista, Windows 7 also will have Home Basic edition that will only be sold in emerging PC markets "for customers looking for an entry-point Windows experience on a full-size value PC," according to Microsoft.
Making all editions of Windows 7 available on small form-factor PCs, widely known as netbooks, is an especially strategic move for Microsoft, as the same was not true for Vista.
Netbooks, also called mini-notebooks because they are smaller than typical PCs, have become an important segment of the PC market, the overall growth of which has been stunted by the current global economic crisis. In fact, Microsoft blamed sales of netbooks partially for missing its financial guidance for its fiscal second-quarter earnings last month, saying the sale of these devices cut into the PC market.
Because of its hardware footprint, it is difficult to run Vista on netbooks, which mainly run XP or Linux. Having Windows 7 running on these devices will give users an upgrade path from XP and should put Microsoft on surer footing in that market.
Vista also had , and features, functionality and hardware requirements differed among them.
This is also true of Windows 7 editions, with the premium versions having more features and functionality than the basic versions. However, Microsoft said it plans to remove some disparities between the different SKUs of Windows 7 by making them all a "superset of one another," so if people decide they want to upgrade from, for example, Home Premium to Professional, they won't lose any functionality from their previous version in that transition, it said.
"With Windows 7 there is a more natural progression from one edition to the next," Microsoft said.
Microsoft has targeted late this year or early next year for the release of Windows 7. The OS is currently in its first public beta, but Microsoft said last week there would be no beta 2, as there typically is with its software products. Instead, the next release of Windows 7 will be a nearly completed release candidate.