Download DynaGen project, install it, download from IS the .zip file 
with IOS images, configure DynaGen host and upload a screenshot of
"show version" command running inside your virtual Cisco box.

Please, do not forget: provided IOS images are non-public, use them
only for LaBAK purposes.

Resources:
  http://dynagen.org/
  http://www.ipflow.utc.fr/index.php/Cisco_7200_Simulator
  http://www.gns3.net