Uso questo metodo qua:

codice:
protected void lbExport_Click(object sender, EventArgs e)
    {
        DisableControls(MainTable);
        Response.ClearContent();
        Response.AddHeader("content-disposition", "attachment; filename=tabella.doc");
        Response.ContentType = "application/word";
        StringWriter sw = new StringWriter();
        HtmlTextWriter htw = new HtmlTextWriter(sw);
        MainTable.RenderControl(htw);
        Response.Write(sw.ToString());
        Response.End();
    }