How to determine Windows 7 is 32bit or 64bit?

View the System Information window

1. Click Start
   
   type system in the Start Search box, and then click System Information in the Programs list
2. When System Summary is selected in the navigation pane, the operating system is displayed as follows:

• For a 64-bit version operating system, x64-based PC appears for the System type under Item.
• For a 32-bit version operating system, x86-based PC appears for the System type under Item