NetTimer security hardware appliance

I have a firewall router, I'd like to know if it's really worth it buying something like this for additional protection. I would like to know what you guys think.

I found this security appliance through: happyhacker.org

The products website is : Net Timer

It stated that:

The NETimer is an easy to install hardware layer of security that protects high-speed Internet users against hacker attacks and other unwanted intrusions. The NETimer sits on the connection between the high-speed modem and the personal computer. It keeps a personal computer disconnected from the Internet when it's not being used for Internet access. The NETimer permits personal computer users to work on non-Internet-related applications, protected from unwanted intrusions via their "always on" high-speed connection. By limiting the user's exposure time to their broadband connection, the NETimer, when disconnected, prevents Trojan horse programs, hackers, denial of service attacks, and information or identity theft.