var i=-400, ii=100;
function einfliegen(){
var pic = document.getElementById('nav_index');
var endPos = -2;
var opacityEnd = 0;

if (i<=endPos){
i = i + 16;
pic.style.left=i;
}
else if (ii>=opacityEnd){
ii = ii - 10;
pic.style.filter="alpha(opacity="+ii+")";
}
window.setTimeout('einfliegen()',0);
}