Ars Technica posted an article yesterday about three possible upgrade editions for users who are using Windows Vista and want to upgrade to Windows 7 later on.

Those who are using the Home Premium Edition can upgrade to the Home Premium Edition of Windows 7. The users of the Ultimate Edition can upgrade to Windows 7 Ultimate Edition. Lastly, if the user has a Business Edition, then he or she can buy the Professional Edition to upgrade his or her operating system.

Although these options are not confirmed, the author of the article notes that he is told that this is what Microsoft is considering at the moment.

Source: Ars Technica