//右クリックの禁止

function forbidIt(){ 

        if(document.all){ 
                if(event.button == 2){ 
                        alert("ＮＯ！");
                }
        }else if(document.layers){
                if(myEvent.which == 3){ 
                        alert("ＮＯ！");
                }
        }
}

if(document.layers)document.captureEvents(Event.MOUSEDOWN);
document.onmousedown = forbidIt;