I had to capture an answer file for our x86 & x64 image.
it seems that the answer file contains two lines that are different.
x86
Component-0=Program Files32
Component-1=RootLevel32
x64
Component-0=Program Files64
Component-1=RootLevel64
I am now using a vbs script to decide which answer file to use.
'-----------------------------------------------------------------------------------------------
' -- IS SYSTEM x86 or x64
'-----------------------------------------------------------------------------------------------
DIM WSHELL, WSHELL_ENV, PROC_ARCH, OS_ARCH_TYPE
SET WSHELL = CreateObject("WScript.Shell")
SET WSHELL_ENV = WSHELL.Environment("Process")
PROC_ARCH = WSHELL_ENV("PROCESSOR_ARCHITECTURE")
If PROC_ARCH = "x86" Then
OS_ARCH_TYPE= WSHELL_ENV("PROCESSOR_ARCHITEW6432")
If OS_ARCH_TYPE = "" Then
OS_ARCH_TYPE = "x86"
End if
Else
OS_ARCH_TYPE = "x64"
End If