datetime parse w/o time

I am retrieving datetime from DB and updating them.
txtboxDate.Text = GridView1.SelectedRow.Cells[8].Text;
The output I am getting is like 3/20/2013 12:00:00 AM . How can I convert that to  20/03/2013

aspx:
<tr>             <td>                 fixedDate:             </td>             <td>                 <asp:TextBox ID="txtboxDate" runat="server"></asp:TextBox>                 <asp:CalendarExtender ID="CalendarExtender4" TargetControlID="txtcalFixed ...