VBScriptで、32 ビットまたは 64 ビットの Windows OS を実行しているかどうかを判断

strOSArch = GetObject("winmgmts:root\cimv2:Win32_OperatingSystem=@").OSArchitecture
If Instr(strOSArch,"64") <> 0 Then
	'OSが64ビット
	MsgBox "64"
Else
	'OSが32ビット
	MsgBox "32"
End if

以下は完璧じゃないっぽい

Dim WshShell
Dim WshProcEnv
Dim system_architecture
Dim process_architecture

Set WshShell =  CreateObject("WScript.Shell")
Set WshProcEnv = WshShell.Environment("Process")

process_architecture= WshProcEnv("PROCESSOR_ARCHITECTURE") 

If process_architecture = "x86" Then    
    system_architecture= WshProcEnv("PROCESSOR_ARCHITEW6432")

    If system_architecture = ""  Then    
        system_architecture = "x86"
    End if    
Else    
    system_architecture = process_architecture    
End If

ネタ元

code-examples.net
docs.microsoft.com