keyboard arduino interface

i was wondering is it possible to use a keyboard as a input for arduino using serial transfer ... as in having my keyboard connected to my pc and then my arduino connected to the pc ... then pressing a button on the keyboard to turn on a led or something

Here is a simple way using a IR remote as a wireless keyboard.

You need some application running on the PC that detects keypresses and sends something to the Arduino, via the serial port. What application is going to do that?