function Validate()
{
     var Msg="";

     if (document.getElementById("first_name").value.length == 0)
     { Msg=Msg + "* Your First Name\n"; }
	 
     if (document.getElementById("last_name").value.length == 0)
     { Msg=Msg + "* Your Last Name\n"; }

     if (document.getElementById("email").value.length == 0)
     { Msg=Msg + "* Your Email Address\n"; }
	 
     if (document.getElementById("confirm_email").value.length == 0)
     { Msg=Msg + "* The Confirmation of Your Email Address\n"; }

     if (document.getElementById("message").value.length == 0)
     { Msg=Msg + "* A Message\n"; }

	if (Msg != "")
	{ alert('Sorry, but before proceeding, you\nmust fill-in the following field(s):\n\n' + Msg); }

	else
     { return true; }

	return false;
}

document.getElementById("contactform").onsubmit=Validate;