Dehabilitar el boton derecho del mouse

function clickIE(){
if (document.all) return false;
}

function clickNS(e){
if (document.layers||(document.getElementById&&!document.all)){
if (e.which==2||e.which==3){
return false;
}
}
}

if (document.layers){
document.captureEvents(Event.MOUSEDOWN);
document.onmousedown=clickNS;
}else{
document.onmouseup=clickNS;
document.oncontextmenu=clickIE;
}