Windows 7 is available in two flavors: 32-bit and 64-bit. The differences between these two editions boil down to one primary subject: memory. 64-bit systems can address more than 4GB of RAM, while 32-bit systems are generally limited to using roughly 3.2GB of RAM. In other words, if your system can run Windows 7 64-bit, you probably should do so.
The easiest way to check whether or not your computer is 64-bit capable is to download the tool SecurAble and run it. The program will instantly tell you the “maximum bit length” of your processor. If it’s 64, you can run Windows 7 64-bit. If it’s 32, you can only run Windows 7 32-bit.
Note that the only significant drawback to Windows 7 64-bit is that some hardware drivers may not be compatible with the architecture. Make sure you check the manufacturer websites for third-party peripherals, graphics cards and other components of your system to ensure 64-bit compatibility or download new 64-bit compatible editions.