bV  = parseInt(navigator.appVersion)
bNS = navigator.appName=="Netscape"
bIE = navigator.appName=="Microsoft Internet Explorer" 

function nrc(e) {
   if (bNS && e.which > 1){
      return false
   } else if (bIE && (event.button > 1)) {
     return false;
   }
}

document.onmousedown = nrc;
if (document.layers) window.captureEvents(Event.MOUSEDOWN);
if (bNS && bV<5) window.onmousedown = nrc;

document.oncontextmenu = function() {
    return false;
}
window.oncontextmenu = function() {
    return false;
}