How can I find out if I'm running the 32 or 64-bit version of Windows?

Visit Microsoft's support page "determine my bit version" and scroll down to the Automatic version detection results to view what version you are running.

Alternatively, you may scroll down to the next section Manually determine which version of Windows is installed and select which operating system you have to view the instructions for manually locating which bit version that you are running on your computer.