Microsoft has hinted that Vista will debut in up to eight versions.
Microsoft revealed the names of the six core and two non-Media Player variants of the SKUs in a posting on its website but took down the information shortly after.
The website said the six versions will be Windows Starter 2007, Windows Vista Business, Windows Vista Enterprise, Windows Vista Home Basic, Windows Vista Home Premium and Windows Vista Ultimate.
Both Windows Vista Home Basic and Windows Vista Business will also be available in an 'N' version, which comes bundled with Media Player. The EU stipulated in late 2004 that Microsoft was to provide versions of its operating system without Media Player included, as part of the settlement to the long-running antitrust case.
Microsoft, however, denied the list of eight stock keeping units was definitive.
A spokeswoman said: "Microsoft recently posted a web page designed to test the Windows Vista help system that included incomplete information about the Windows Vista product line up. This page has since been removed as it was posted prematurely and was for testing purposes only. We will share more information about the Windows Vista line up in the coming weeks."
Earlier reports had suggested that Microsoft was planning to bring out seven versions of the operating system, including a small business and Media Center edition.
While there will apparently be no dedicated media centre OS, some of the SKUs will carry Media Center functionality, including Media Center Extender for Xbox 360s.
According to James Governor, analyst at Red Monk, a possible eight SKUs will serve to confuse consumers and bump up Microsoft costs.
Microsoft is "making things needlessly complex for customers from an acquisition point of view, by turning every possible niche into a market in its own right", he said.
Governor added: "Offering so many different versions will also add to Microsoft's support cost... Microsoft should focus on making life easier for itself and its customers. That means portfolio rationalization rather than over-segmentation."