Is there a free VPN software that uses network like ad hoc or computer to computer network?

Is there a free VPN software that doesn't require internet and has no virus or maliware that uses networks like ad hoc network which is also a computer to computer network. I am useing windows vista. Give specific detail on how to install and use the program. Has to be easy to install. Like a installer to it. Has to be easy to use like hamachi but useing a ad hoc network. Exept that doesn't require the internet or router.