Hotkey to disable internet

Hey guys.

I need a way (software, windows settings, whatever works) to disable my computer's internet (or block the connection of an individual process) by simply pressing a key (not mouse) in the keyboard.

Thanks for the help.

EDIT: Windows vista just in case. The disabling on the internet has to be close to instant as soon as I press said key (minimum delay).

EDIT: The key should be global since I'll be pressing it while using a specific process and not on the desktop or anything.