I have this script for a search box
but to activate the search you have to click with the mouse on the picture to activate the search
how can i make it work that just an enter will start the search

<div id="search">
<table cellpadding="0" cellspacing="0" border="0">
<tr align="center">
<td>
<input type="text" name="txtSearchValue">
</td>
<td>
<img src="site_images/find.gif" onclick="parent.main.location.href = 'zoekframe.php?strZoek=' + txtSearchValue.value;" style="cursor:'hand'">
</td>
</tr>
<tr>
<td colspan="2">
<a href="meerzoek.php" target="main">Uitgebreid zoeken</a>
</td>
</tr>
</table>
</div>