You may be right, but I haven’t taken any time to look and see what AVG Internet Security Suite has for disabling the internet connection.
This is actually going to be my wife’s computer and sometimes things that are simple right there on the desktop end up working best.
We’ve been having a problem of late with her just leaving her current computer connected to the internet 24/7… but, what can you do? 
@KM Richards
have you ever thought of dumping windows 7 for a Linux distribution?
I’d ask for a shortcut - “Make everything secure”
Why, is having a shortcut on the desktop less secure?
Well that still needs two clicks - one to minimise everything so you can see the desktop and then the second to activate your shortcut.
I can’t see how that is any different from one click on the firewall icon in the system tray and then a second click on the big red stop button that most firewalls provide for when you need to completely block internet access. The only difference is the time you spent setting up your shortcuts.
how do you get the internet i.e. cable, fiber optic, wireless
for cable modems or other wired setups
or you could by a connector and leave it on top of you desk and disconnect it when done. as mentioned by Aleksejs
The above method is patent pending.
You could always move your box to a more “unpluggable” convenient location 
I know it’s not what you’re directly after, but it is a “work around”. Or unplug the other side of the ethernet cable that connects to your router, perhaps place that somewhere on your desk, then there’s no reaching under the desk anymore!
If you “Open network and sharing center” under Win7 you will see what adapters are connected, if you click on it, a dialog will open and at the bottom below the Activity area you can “Disable”
OR
->Control Panel\Network and Internet\Network Connections
Right click “Disable” on whatever adapter is active.
I use Panda Global Protection as my firewall and anti-virus program, the firewall side of it has an area where you can specify what type of connect each program can make (inbound only, outbound only, both ways or no access), it can even be set to what ports and IP address they can use. Have a look through the firewall settings for the firewall software that your using, you may have a similar option
Actually, the opposite is true…all that booting up will cause alot of wear and tear on your hardware causing it to fail quicker than if you simply left it on all the time.
Besides, and idle computer uses very little electricity with today’s modern energy efficient hardware
This is why the government, schools, and most industry computers run non-stop 
OK, so I was able to find a different wndow to use when I need to disable the connection, and I was able to make a shortcut to the desktop
So, I now have one shortcut to click on to activate
and a different shortcut to click on to disable
What more could one ask for in an internet connection 
Why do you want this switch?
Are you serious? Why not just plug out your network cable?
At least it should be more cool looking…
http://www.cracked.com/blog/wp-content/uploads/2010/06/big-knife-switch.png