The following can not update to Windows 7 RTM:
Windows 95, Windows 98, Windows Millennium Edition, Windows XP, Windows Vista® RTM, 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.