now I can compile and upload it to my Arduino 
but when I connect the data and the clock wires from a ps/2 cable to the pc and to the arduino on digital pin 3 and 2 the Arduino doesn't starts anymore :'(. And when I reset it my pc says that the connected hardware isn't ok and I don't see the com port of it. When I disconnect the ps/2 wires and reset it it works fine again :-?
Does someone has any idea what I'm doing wrong?