LogMeIn Hamachi is a zero-configuration virtual private networking (VPN) application.   In other words Hamachi is a program that allows you to arrange multiple computers into their own secure network just as if they were connected by a physical network cable. Hamachi is fast, secure and simple. Its core version is also free.

HamachiSetup-1.0.1.5-en.exe (895KB)

http://www.hamachi.cc/

OpenVPN is a full-featured SSL VPN solution which can accomodate a wide range of configurations, including remote access, site-to-site VPNs, WiFi security, and enterprise-scale remote access solutions with load balancing, failover, and fine-grained access-controls.

openvpn-2.0.9-install.exe (978KB)

http://openvpn.net/