1) Go to this page:
2)Download and install the "com_securityimages" file using the Joomla Component Installer
3)From the same page, download the correct patch version for your version of Joomla (e.g. 1.0.14).
4) Backup your Joomla installation
5) Copy over the files from the patch archive into your root Joomla directory
6) You're ready to rumble! Lots of it comes default configured, and you can get a wide array of additional options through the "Security Images" component control panel.
This worked great for me, and its the best one I've tested because you don't need to add an additional module, you patch the existing one which makes it much easier because the ones that come in separate modules, you have to go through and manually change some of the links to the Log in and register pages!