Microsoft has released a guide for Windows users who wants to upgrade their Windows OS like Windows Vista or Windows XP to Windows 7.
This guide is titled as "
Windows 7 Upgrade Paths" which is free downloadable from Microsoft Downloads at
Upgrade Paths to Windows 7.
I believe most of the Windows users who are willing to upgrade to Windows 7 have Windows Vista as their installed Windows operating systems. For a successful Vista upgrade Windows7 has the prerequisite that Windows Vista has Service Pack SP1 or Service Pack SP2 should be installed.
Supported Upgrade Scenarios for Windows7 Upgrade
The following upgrade paths to Windows7 are supported officially by Microsoft as illustrated in the "Windows 7 Upgrade Paths" document.
How to upgrade Vista to Windows7
| From Windows Vista (SP1 or SP2) | Upgrade to Windows 7 |
| Business | Professional, Enterprise, Ultimate |
| Enterprise | Enterprise |
| Home Basic | Home Basic, Home Premium, Ultimate |
| Home Premium | Home Premium, Ultimate |
| Ultimate | Ultimate |
| From Windows 7 | Upgrade to Windows7 |
| Enterprise | Enterprise |
| Home Basic | Home Basic |
| Home Premium | Home Premium |
| Professional | Professional |
| Starter (x86 only) | Starter (x86) |
| Ultimate | Ultimate |
| From Windows7 | Anytime Upgrade to Windows 7 |
| Home Basic | Home Premium, Professional, Ultimate |
| Home Premium | Professional, Ultimate |
| Professional | Ultimate |
| Starter | Home Premium, Professional, Ultimate |
Unsupported Upgrade Scenarios for Windows7 Upgrade
Beside supported upgrade scenarios for Windows 7, Microsoft has written down the unsupported cases where an upgrade to Windows7 is impossible.
Any upgrade to Windows7 from the following prior operating systems Windows 95, Windows 98, Windows ME (Millennium Edition), Windows XP, Windows Vista RTM (you should at least installed the SP1 or better SP2 for a Windows 7 upgrade, Vista upgrade Windows7 requires SP1 or SP2), Windows Vista Starter are not supported .
Any upgrade from Windows 7 RTM prior versions like Windows 7 M3, Windows 7 Beta, Windows 7 RC, or Windows 7 IDS version upgrades to Windows 7 are not supported.
Upgrades to Windows 7 from Windows servers like Windows NT Server 4.0, Windows 2000 Server, Windows Server 2003, Windows Server 2008, or Windows Server 2008 R2 are not supported as well.
Upgrades from 32-bit system to 64-bit systems or 64-bit to 32-bit systems are not supported (x86 to x64 or x64 to x86).
In place cross language upgrades like from German to English(US), etc. are not supported.
Pre-release in-place upgrades across milestones like Windows 7 RC to Windows 7 RTM versions are not supported.
But I know that a friend has upgraded his system by editing a Windows system file for minimum supported edition for upgrade but of course is not supported by MS.