Try this
<script type="text/javascript">
function showImage()
{
document.getElementById("image").style.display="inline";
document.getElementById("image").src = 'your image path';
}
function hideImage()
{
document.getElementById("image").style.display="none";
document.getElementById("image").src = '';
}
</script>
<asp:LinkButton ID="LinkButton1" runat="server" OnMouseOver="showImage();" OnMouseOut="hideImage();">LinkButton</asp:LinkButton>
<img src="" id="image" alt="" width="100px" height="50px" style="display:none;" align="right"/>
Thanks
Ashish