"Method 2: View the System Information window
1.Click Start, and then click Run.
2.Type winmsd.exe, and then click OK.
3.When System Summary is selected in the navigation pane, locate Processor under Item in the details pane. Note the value. ?If the value that corresponds to Processor starts with x86, the computer is running a 32-bit version of Windows.
?If the value that corresponds to Processor starts with IA-64 or AMD64, the computer is running a 64-bit version of Windows."
From the link I gave above. If the processor is x86 it's a 32 bit processor. If it shows 64 then it's 64-bit.