<div id="ds1" onmouseover="move1(event)" onmouseout="move2(event)">
function move1(evt)
{(evt.target || evt.srcElement).style.color="#00BFFF"}
Но в вашем случае лучше
<div id="ds1" onmouseover="move1(this)" onmouseout="move2(this)">
function move1(el)
{el.style.color="#00BFFF"}