$.preloadImages = function () {
	    if (typeof arguments[arguments.length - 1] == 'function') {
	        var callback = arguments[arguments.length - 1];
	    } else {
	        var callback = false;
	    }
	    if (typeof arguments[0] == 'object') {
	        var images = arguments[0];
	        var n = images.length;
	    } else {
	        var images = arguments;
	        var n = images.length - 1;
	    }
	    var not_loaded = n;
	    for (var i = 0; i < n; i++) {
	        $(new Image()).attr('src', images[i]).load(function() {
	            if (--not_loaded < 1 && typeof callback == 'function') {
	                callback();
	            }
	        });
	    }
	}
	
	function isValidEmail (email){
		return (/^([a-z0-9_\-]+\.)*[a-z0-9_\-]+@([a-z0-9][a-z0-9\-]*[a-z0-9]\.)+[a-z]{2,4}$/i).test(email);
	}