If Windows AIK is not installed on the computer (or it is either corrupt or installed incorrectly), the wizard will offer you the option to install it, or to enter the path to your Windows AIK folder.
For proper functioning, Windows AIK version 936330AIK needs to be installed (http://www.microsoft.com/Downloads/details.aspx?familyid=94BB6E34-D890-4932-81A5-5B50C657DE08&displaylang=en).