<asp:TemplateColumn HeaderText="Caricare">
<HeaderStyle HorizontalAlign="Center" Width="80px"></HeaderStyle>
<ItemStyle HorizontalAlign="Center"></ItemStyle>
<ItemTemplate>
<a href="#" onclick="window.open('update.aspx?id=1&cliente=2&t ot=3','Modifica','width=500,height=500')">
Modifica</a>
</ItemTemplate>
</asp:TemplateColumn>

koning