Fijate masomenos asi haber si te funciona...
Código PHP:
<STYLE>
.hideable { position: relative; visibility: visible; }
</STYLE>
<script type="text/javascript">
<!--
function showMe (it, box) {
var vis = (box.checked) ? "block" : "none";
document.getElementById(it).style.display = vis;
}
//-->
</script>
<FORM NAME="form0">
<TABLE>
<?php
include ("configuracion.php");
$sql = "SELECT * FROM servidores ORDER BY id";
$res = do_sql($sql);
$i=0;
while ($row = mysql_fetch_array($res)) {
$i++;
?>
<TR>
<TD VALIGN="top"> *
<input type="checkbox" name="id_servidor[]"*onclick="showMe('div<?php echo $i ?>', this)" value="<?php echo $row['id_servidor']?>"><?php echo $ide; ?>
<br />
</TD>
<TD>
<DIV id="div<?php echo $i ?>" style="display: none">
<SPAN ID="contenido" CLASS="hideable">
Enlace: <INPUT TYPE='text' NAME='enlace_servidor' SIZE=15 MAXLENGTH=100>
</SPAN>
</DIV>
</TD>
</TR>
<?php } ?>
</TABLE>
</FORM>