INTRODUCTION
This article helps you to determine whether a computer is running a 32-bit or 64-bit version of Windows.
STEP-BY-STEP GUIDE
Due to the constantly changing editions of Windows involved, this article refers to a Microsoft site where the information can be found. The site referred below will try to automatically detect which version of Windows you are running. In case it fails to detect, then manual detection mechanisms are also provided there. Once you open the below mentioned page, watch for the section titled "Automatic version detection results".
...