Preventing right click in websites

var message="Sorry, Right Click is disabled.";

function click(e)
{
if (document.all)
{
if (event.button == 2)
{
alert(message);
return false;
}
}
if (document.layers)
{
if (e.which == 3)
{
alert(message);
return false;
}
}
}
if (document.layers)
{
document.captureEvents(Event.MOUSEDOWN);
}
document.onmousedown=click;