Prova così, a me funziona correttamente.
<head>
.
.
.
<style>
a:link {text-decoration: none; color: blue}
a:visited {text-decoration: none; color: blue}
a:hover {text-decoration: none; color: blue}
.c1 {background: url(images/bottone_off.png) no-repeat center; text-align: center; font-family: arial; font-size: 9pt; color: white; cursor: hand; padding-top: 1px}
.c2 {background: url(images/bottone_on.png) no-repeat center; text-align: center; font-family: arial; font-size: 9pt; color: blue; font-weight: bold; cursor: hand padding-top: 1px}
</style>
.
.
.
</head>
<body>
.
.
.
<table border="0" cellpadding="0" cellspacing="0" width="85">
<tr>
<td class="c1" onmouseover="this.className='c2'" onmouseout="this.className='c1'" onclick="document.location.href='linkallapaginachevuoi' ">
testo link
</td>
</tr>
</table>
.
.
.
</body>
Ovviamente cambia ciò che devi cambiare (colori, nomi delle immagini, link, etc.)