1. Click START. 2. Right click on MY COMPUTER. 3. Select PROPERTIES. You will see “System type” in the “System” section, and that will tell you whether you are running the 32 or 64-bit version of Windows 7.
"This article automatically determines whether a computer is running a 32-bit or 64-bit version of Windows. This article also describes how to manually determine whether a computer is running a 32-bit or 64-bit version of Windows. Generally, a computer's bit count indicates how much data it can process, the speed with which it can process the data, and the maximum memory capacity. In order to optimize the computer's performance, the bit count of the operating system that is installed on the computer should match the bit count of the computer itself."