What is the "key click" you're talking about? Is the OS producing a sound whenever you press a key on the keyboard? Does this happen only in some programs, or all the time?
Thanks for the reply. The noise that's annoying people is the clicking noise coming from the mouse buttons on the mouse pad. I thought it was from the keys but it's not. I don't think there's anything I can do about it, because they make the same noise when the machine's switched off. I've started tapping the mouse pad instead.