What is the difference between 32 and 64-bit Windows?
The terms 32-bit and 64-bit refer to the way a computer's processor (also called a CPU), handles information. The 64-bit version of Windows handles large amounts of random access memory (RAM) such as those required for high end 3D gaming.
Most new computers are 64-bit, particularly notebooks.
To find out if your computer is running a 32-bit or 64-bit version of Windows in Windows 7 or Windows Vista, do the following:
Open System by clicking the Start button , right-clicking Computer, and then clicking Properties.
Under System, you can view the system type & it will clearly state if it is 64-bit
If your computer is running Windows XP, do the following:
Right-click My Computer, and then click Properties
If you don't see "x64 Edition" listed, then you're running the 32-bit version of Windows XP
If "x64 Edition" is listed under System, you're running the 64-bit version of Windows XP