Security Basics: Multi-Factor Authentication

[avasquez80 () gmail com]

I'm working on a project that involves giving our employees OWA and intranet access through a Juniper SSL VPN from the 
web. Currently a hand full of employees are using RSA keys to authenticate. While we can not go out and buy over 3000+ 
RSA keys for every employee I'm looking for an alternate sign on solution. My main goals are preventing someone from 
the outside brute forcing their way in. I have seen one solution that looked promising called vidoop. They offer a SSO 
which has pictured images as added security. I would be curious to what others are using for OWA and other internal 
access solutions.

Thanks.