[This is preliminary documentation and subject to change.]
Recommendation (Designed for Microsoft® Windows® Logo)
Your application should not write anything to the Windows \system or \system32 directory. In particular, they should not place shared DLLs or executables to the Windows system directories.
On Windows NT 5.0, the operating system will support a mode in which the \system32 directory is read-only and unavailable to applications and installers. This will be part of the Zero Administration for Windows effort to reduce DLL conflicts and other shared component problems.
Fonts and Control Panel applications can continue to be installed in the appropriate Windows system directory.
Applications may update system components in the Windows system directories if they use a Microsoft update package to do so.