How to disable Macbook internal keyboard

My MBP is 10.7.5. Unfortunately, the internal keyboard was spoiled by my baby.
So here is how to disable it and use an external apple keyboard.

Open terminal and type the following:
sudo kextunload /System/Library/Extensions/AppleUSBTopCase.kext/Contents/PlugIns/AppleUSBTCKeyboard.kext/

To enable it again:
sudo kextunload /System/Library/Extensions/AppleUSBTopCase.kext/Contents/PlugIns/AppleUSBTCKeyboard.kext/

It works like a charm!~ Googled from this link: http://forums.macrumors.com/showthread.php?t=433407