How to disable Inspiron 1150 Internal Keyboard?

My friend has an Inspiron 1150 whose keyboard has seen better days.  One key is broken off, and the control key periodically sticks, even when it hasn't been touched.  Originally we got him an external USB keyboard, and things were tolerable for a while, but now it seems the control key is sticking more and more often.  I know its not the USB keyboard fault, as it behaves like this with several keyboards.

I can alos see a dried liquid like stain under one of the control keys, though of course, he never spilled anything on the laptop. :)

The easiest solution that comes to mind is taking the built in keyboard out of the mix.  I couldn't find an option to do this in the bios setup, though since you can disbale the touch pad via the bios, it seems like a option that should be there.  I've also considered just removing the keyboard from the system, but I'm concerned that the machine with either not boot with the keybaord removed, or turning on the laptop without the keyboard installed may damage the system.

Does anyone have any suggestions?  I realize replacing the keyboard is an option, but with a perfectly good USB keybaord already in place, that would be our last resort.

BTW, he's running windows XP service pack 3.