I thought so too, first i tried

function IsX64: Boolean;
begin
  Result := IsWin64;
end;

But same result. perhaps it is not supported on VM, I am running a 32bit Windows XP VM and there it returns True.

>You should check Windows not hardware http://www.jrsoftware.org/ishelp/index.php?topic=isxfunc_iswin64
>
>>Using innosetup for the setup procedure, I need to run a file after setup, depending on 32bit or 64 bit OS. I
>tried a few flags to check if the OS is 64 bit, but Innosetup seems to ignore those:
>>

>>[Code]
>>function IsX64: Boolean;
>>begin
>>  Result := (ProcessorArchitecture = paX64);
>>end;
>>
>>[Files]
>>; MsSql client:
>>Source: "..\Resources\SQLRuntimeFiles\sqlncli.msi"; DestDir: "{tmp}"; Components: CompleteClient; Check: not IsX64
>>Source: "..\Resources\SQLRuntimeFiles\sqlncli_x64.msi"; DestDir: "{tmp}"; DestName: "sqlncli.msi"; Components: CompleteClient; Check: IsX64
>>
>>[Run]
>>Filename: {sys}\msiexec.exe; Parameters: /i {tmp}\sqlncli.msi; WorkingDir: {tmp}; StatusMsg: Installing SQL Server Native Client Drivers.; Flags: runascurrentuser;
>>

>>It looks like it ignores the check and always copies both files. So when running the resulting setup.exe on a 32bit OS it gives the error message that it is not supported. What am I missing here?