http://blogs.msdn.com/ntdebugging/archive/2008/06/03/how-to-debug-wow64-applications.aspxHello, my name is Venkatesh Ganga, and I’m an Escalation Engineer on the Microsoft Platform Global Escalation Services team. Recently, I worked on an issue where registry reflection was not happening while installing 32bit Office under the system account.en-USCommunityServer 2.1 SP1 (Build: 61025.2)http://blogs.msdn.com/ntdebugging/archive/2008/06/03/how-to-debug-wow64-applications.aspx#8573328Wed, 04 Jun 2008 16:41:29 GMT91d46819-8472-40ad-a661-2c78acb4018c:8573328Marc Sherman<p>Does .effmach x86 differ at all from using !wow64exts.sw ?</p> <p>thanks</p>http://blogs.msdn.com/ntdebugging/archive/2008/06/03/how-to-debug-wow64-applications.aspx#8573784Wed, 04 Jun 2008 21:37:10 GMT91d46819-8472-40ad-a661-2c78acb4018c:8573784Skywing<P>The recommended way to do this, or at least so I thought, was to use the built in ".effmach &lt;arch-type&gt;" command (e.g. "x86", "amd64", ...).</P> <DIV class=commentowner>[Internally .effmach and !wow64exts.sw make same call to change the processor mode that debugger uses. !wow64exts.sw is written to automatically switch between 32bit and 64bit mode whereas .effmach needs the machine type as input.]</DIV>