var slideshows = new Array("img1.jpg","img2.jpg","img3.jpg");
var curIndex = 0;

function init() {
	setInterval( 'goSlides()', 3000 );
}

function goSlides() {
	curIndex++;
	if (curIndex >= slideshows.length) 
		curIndex = 0;
		
	document.getElementById('slideshow').style.backgroundImage = 'url(images/' + slideshows[curIndex] + ')';
}