MouseOver and MouseOut in JavaScript

<script type="text/javascript">
function mouseOver()
{
document.getElementById("b1").src="wp-includes/images/readmore_big.jpg"
}
function mouseOut()
{
document.getElementById("b1").src="wp-includes/images/readmore_big_blur.jpg"
}
</script>


<div align="right">
<a href="http://www.iirgroup.com/researchoracle/viewreport/show/25102" target="_blank" onmouseover="mouseOver()" onmouseout="mouseOut()">
<img border="0" alt="Read More Reports on researchoracle.com" title="Read More Reports on researchoracle.com" src="wp-includes/images/readmore_big_blur.jpg" id="b1" /></a>  
</div>