OpenVPN is the free open source project of VPN solutions.  I installed the GUI version on my windows 2003 server a long time ago.  However, I tried hard  to configure it that time by following some web tutorial but couldn’t get it to work properly.  Today I found two posts in Chinese which help me to finally get it to work.

Links below:

Windows 下使用 CA 验证的 OpenVPN Server 的配置方法 (by ELM)

OpenVPN之以太网桥接 (by 温占考 from OpenVPN.net)