$(document).ready(function(){
	window.setInterval("changeImg()", 7000);
});
var image = 'firstImg';	
function changeImg()
{
	switch(image){
		case 'firstImg':
		var nextimage = 'secondImg';
		break;
		case 'secondImg':
		var nextimage = 'thirdImg';
		break;		
		case 'thirdImg':
		var nextimage = 'firstImg';
		break;
	}
	
	$("#"+image).fadeOut(300, function(){
		$("#"+nextimage).fadeIn("slow");
	});
	image = nextimage;
}