Only works if your internet and internal network are separated.For other then dialup you will usually find the device manager a more useful tool where you simply right click on the network adapter or other device listing and choose the disable option. Once done simply try getting online by opening up the browser you are using. For re-enabling you repeat the steps mentioned and now see the enable option instead. You will probably need to reboot the system on some occasions if you see problems getting back on.
Virtually any firewall can allow you that. Depending on the firewall it will vary the complexity but virtually all firewalls have a means of differentiating local and external traffic -- just lockdow the external when you want toAlso I would like a program that could turn of internet will a push of a button or like a shortcut on the desktop or like a floating task box with a button to turn off the internet