Setup for Windows
If you want to write a custom configuration, or don't want to use the HDAconnect tool, this will help you set up OpenVPN on a Windows XP/Vista/7 machine, without much of a problem if you have the default settings for Amahi installed and your port forwarding set to 1194 UDP.
Step 1: Download OpenVPN GUI from http://openvpn.se/
(Click the stable link on the left, choose the installer.)
Step 2: Install OpenVPN
You can just click through, and install any drivers it asks you for.
Step 3: Writing a config file
Open a text editor of your choice, and copy the following:
remote YOURIPHERE 1194 #This needs to be changed per your external IP address
route 192.168.1.0 255.255.255.0 vpn_gateway 3 #Use your network IP address, usually a router is at default 192.168.1.1
You only need to change the bolded text.
Step 4: Save the config file to the directory you installed OpenVPN to
There is a folder labeled configs make sure you have the extension saved as *.opvn using the "all files" option.
Step 5: Launch
Launch OpenVPN GUI, and you should be ready to go. Right click on the Icon, select the config file you wrote, connect, log in, and enjoy.