A. Goto the %windir%\SysWOW64 folder on your 64-bit installation and do a listing of all the content, including sub-directories. On a Windows Server 2008 R2 or Windows 7 full install, it's around 1GB of content. On a Server Core installation, it's about 250MB. This folder contains the Windows on Windows 64 (WoW64) files, so all of this content is required to let the 64-bit OS run 32-bit applications. A 64-bit installation is far larger than a 32-bit installation because, in addition to all its native binaries, a 64-bit install also needs many of the 32-bit binaries to run 32-bit applications.
On Windows Server Core 2008 R2, WoW64 is an optional component. I gave instructions for removing WoW64 in a previous FAQ.
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