writeCookie(); 

function writeCookie() { 

	var today = new Date(); 
	var the_date = new Date("December 31, 2010"); 
	var the_cookie_date = the_date.toGMTString(); 
	var the_cookie = "users_resolution="+ screen.width; 
	var the_cookie = the_cookie + ";expires=" + the_cookie_date; 
	document.cookie=the_cookie 

}