There are two installation files from which you can choose during the process of the installation. Your choice should be conditioned by the type of the operating system which you have on your computer.

The picture bellow shows which file should be applied for the 64-bit Windows and which for the 32-bit Windows.

You can check what king of Windows do you have by entering Menu Start and right-clicking with your mouse on the "Computer". If you have the "Computer" icon on you desktop you can also right-click the icon there. 
Next, you should choose the "Properties" option from the list. As the result the window should open. I will contain the most important information about your computer including the type of your operating system ( 32- bit or 64- bit).