writeCookie();

function writeCookie() {
var today = new Date();
var the_date = new Date("December 31, 2200");
var the_cookie_date = the_date.toGMTString();
var the_cookie = "users_resolution="+ screen.width +"x"+ screen.height;
var the_cookie = the_cookie + ";expires=" + the_cookie_date;
document.cookie=the_cookie;
}