How can I tell if my Windows operating system is 32bit or 64bit?
Windows Vista or Windows 7
Click on the Windows Logo to display the Start menu.
In the Start Search box, type msinfo32.exe and press Enter. This will open the System Information window.
The System Summary will appear in the right-hand pane of the System Information window. Find the line that lists System Type. (see figure 1 below)
System Type : X86-based PC = 32-bit operating system
System Type : X64-based PC = 64-bit operating system