var posX1 = 0;
var speed = 20;
var widthX = (document.getElementById("sponsors_list_1").offsetWidth);
var posX2 = widthX;

function scroller() {
document.getElementById('sponsors_list_1').style.left=posX1+'px';
document.getElementById('sponsors_list_2').style.left=posX2+'px';
posX1--;
posX2--;

if (posX1+widthX<0) {
posX1=widthX;
}

if (posX2+widthX<0) {
posX2=widthX;
}

toutID = setTimeout('scroller()',speed);
}

function stopScroller() {
clearTimeout(toutID);
}

window.onload = function() {
scroller();
}