From http://msdn.microsoft.com/en-us/library/aa384235(VS.85).aspx:
[The information in this topic applies to Windows Server 2008, Windows Vista, Windows Server 2003, and Windows XP/2000. Starting with Windows 7 and Windows Server 2008 R2, WOW64 no longer uses registry reflection and formerly reflected keys are shared instead. For more information, see Registry Keys Affected by WOW64.]
The registry redirector isolates 32-bit and 64-bit applications by providing separate logical views of certain portions of the registry on WOW64. However, the values of some registry keys must be the same in both the 32-bit and 64-bit views.
