Microsoft has now revealed the upgrade paths for Windows 7 detailing the “supported and unsupported upgrade paths for editions of the Windows® 7 operating system.” The full whitepaper can be viewed here. Although you can do a clean installation and completely ignore these paths, you will be limited to the following scenarios if you choose to do an upgrade:
| From Windows Vista (SP1, 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 Windows 7 |
| Enterprise | Enterprise |
| Home Basic | Home Basic |
| Home Premium | Home Premium |
| Professional | Professional |
| Starter (x86 only) | Starter (x86) |
| Ultimate | Ultimate |
| From Windows 7 | Anytime Upgrade to Windows 7 |
| Home Basic | Home Premium, Professional, Ultimate |
| Home Premium | Professional, Ultimate |
| Professional | Ultimate |
| Starter | Home Premium, Professional, Ultimate |
Be warned that the following scenarios are not supported, as outlined in the whitepaper:
- Upgrades to Windows 7 from the following operating systems are not supported:
- Windows 95, Windows 98, Windows Millennium Edition, Windows Vista Starter, Windows 7 M3, Windows 7 Beta, Windows 7 RC, or Windows 7 IDS
- Windows NT® Server 4.0, Windows 2000 Server, Windows Server® 2003, Windows Server 2008, or Windows Server 2008 R2
- Cross-architecture in-place upgrades (for example, x86 to x64) are not supported.
- Cross-language in-place upgrades (for example, en-us to de-de) are not supported.
- Cross-SKU upgrades (for example, Windows 7 N to Windows 7 K) are not supported.
- Upgrades from Windows Vista to Windows N, Windows K, Windows KN, or Windows E are not supported.
- Cross-build type in-place upgrades (for example, fre to chk) are not supported.
- Pre-release in-place upgrades across milestones (for example, Windows 7 RC to Windows 7 RTM) are not supported.
