Suposedly this change inside WindowsXP.Manifest is enough to support both 32 and 64 bits:
Please notice:
processorArchitecture="*"
instead of (modified in two lines):
processorArchitecture="x86"
The above is as per Microsoft instructions:
http://msdn.microsoft.com/en-us/library/windows/desktop/bb773175(v=vs.85).aspx
Anyhow, it does not seem to work properly. Robb, have you been able to make it work ? thanks
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<assembly xmlns="urn:schemas-microsoft-com:asm.v1" manifestVersion="1.0">
<assemblyIdentity
  version="1.0.0.0"
  processorArchitecture="*"
  name="FiveTech Software.FiveWin.32bits"
  type="win32"
/>
<description>Your application description here.</description>
<dependency>
  <dependentAssembly>
    <assemblyIdentity
      type="win32"
      name="Microsoft.Windows.Common-Controls"
      version="6.0.0.0"
      processorArchitecture="*"
      publicKeyToken="6595b64144ccf1df"
      language="*"
    />
  </dependentAssembly>
</dependency>
</assembly>Please notice:
processorArchitecture="*"
instead of (modified in two lines):
processorArchitecture="x86"
The above is as per Microsoft instructions:
http://msdn.microsoft.com/en-us/library/windows/desktop/bb773175(v=vs.85).aspx
Anyhow, it does not seem to work properly. Robb, have you been able to make it work ? thanks