You dont need Javascript. you can do that with CSS.
insert into the links for the username a span and make the link a class "section"
Text Formatted Code
<a class="section" href="/user...">Username<span><img src="/path/"></span></a>
then add the following to your CSS.
Text Formatted Code
.section {
position:relative; /*this is the key*/
z-index:24;
}
.section:hover {
z-index:25;
}
.section span{
display: none;
}
.section:hover span { /*the span will display just on :hover state*/
display:block;
position:absolute;
}