nav1_off = new Image(); nav1_off.src = "images/nav1.gif";
nav1_on = new Image(); nav1_on.src   = "images/nav1_on.gif";
nav2_off = new Image(); nav2_off.src = "images/nav2.gif";
nav2_on = new Image(); nav2_on.src   = "images/nav2_on.gif";
nav3_off = new Image(); nav3_off.src = "images/nav3.gif";
nav3_on = new Image(); nav3_on.src   = "images/nav3_on.gif";
nav4_off = new Image(); nav4_off.src = "images/nav4.gif";
nav4_on = new Image(); nav4_on.src   = "images/nav4_on.gif";

function roll(sname,rname){
    sname.src = rname.src;
}

function signup_validate(f) {
	var AtSym = f.elements.email.value.indexOf('@')
	var dot = f.elements.email.value.lastIndexOf('.')
	var space = f.elements.email.value.indexOf(' ')
	var length = f.elements.email.value.length

	if ((AtSym < 1 ) ||   // '@' can't be first
    	 (dot <= AtSym +1 ) || //one char between '@' and '.'
	     (dot == length - 1 ) ||  //one char after '.'
	     (space  != -1))  //no spaces allowed
	   {  
	    alert("Please enter a valid e-mail address");
	    return false;
	   }
	   
	if (f.elements.email == '') {
		alert('You must provide an e-mail address.');
		return false;
	} 

	f.submit();

}