funzione javascript :

function ConsumoAnnuo()
{
alert('Ciao');
}

<td width="650" bgcolor="whitesmoke">
<div id="Contratti"><table border=0 align=left><tr><td bgcolor=SlateGray align=center><font color=White face=verdana size=2>Codice Contratto</font></td><td bgcolor=LemonChiffon><font face=verdana size=2 color=DarkRed>248491</font></td></tr><tr><td bgcolor=SlateGray align=center><font color=White face=verdana size=2>Impianto N°</font></td><td bgcolor=LemonChiffon><font face=verdana size=2 color=DarkRed>323765</font></td></tr><tr><td bgcolor=SlateGray align=center><font color=White face=verdana size=2>Ubicazione</font></td><td bgcolor=LemonChiffon><font face=verdana size=2 color=DarkRed>Via Roma 3 Reggio Emilia</font></td><td></td><td align=center><input type=Button value='ConsumoAnnuo' onmouseover=JavaScript=style.cursor='hand' onclick=javascript:ConsumoAnnuo('Rossi Luigi')></td></tr></tr> <tr><td>

</tr></table></div>

Giuliano