Give a class say "date" to all TextBoxes
<asp:TextBox ID="txtProductDate" runat="server" ReadOnly = "true" CssClass = "date"></asp:TextBox>
And then use the following
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.6/jquery.min.js" type="text/javascript"></script>
<script src="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/jquery-ui.min.js" type="text/javascript"></script>
<link href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8/themes/base/jquery-ui.css" rel="Stylesheet" type="text/css" />
<script type="text/javascript">
$(function () {
$("[.date").datepicker({
showOn: 'button',
buttonImageOnly: true,
buttonImage: 'http://jqueryui.com/demos/datepicker/images/calendar.gif'
});
});
</script>
