Index: update.module
===================================================================
RCS file: /cvs/drupal/drupal/modules/update/update.module,v
retrieving revision 1.17.2.1
diff -u -p -r1.17.2.1 update.module
--- update.module	23 Sep 2008 10:19:02 -0000	1.17.2.1
+++ update.module	24 Feb 2009 16:37:25 -0000
@@ -189,7 +189,8 @@ function update_theme() {
  * @see _update_cron_notify()
  */
 function update_requirements($phase) {
-  if ($phase == 'runtime') {
+  $frequency = variable_get('update_check_frequency', 1);
+  if ($frequency != 0 && $phase == 'runtime') {
     if ($available = update_get_available(FALSE)) {
       module_load_include('inc', 'update', 'update.compare');
       $data = update_calculate_project_data($available);
@@ -285,6 +286,7 @@ function _update_requirement_check($proj
  */
 function update_cron() {
   $frequency = variable_get('update_check_frequency', 1);
+  if( $frequency == 0 ) return;
   $interval = 60 * 60 * 24 * $frequency;
   // Cron should check for updates if there is no update data cached or if the configured
   // update interval has elapsed.
Index: update.report.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/update/update.report.inc,v
retrieving revision 1.10.2.2
diff -u -p -r1.10.2.2 update.report.inc
--- update.report.inc	28 Aug 2008 08:14:56 -0000	1.10.2.2
+++ update.report.inc	24 Feb 2009 16:37:25 -0000
@@ -10,7 +10,8 @@
  * Menu callback. Generate a page about the update status of projects.
  */
 function update_status() {
-  if ($available = update_get_available(TRUE)) {
+  $frequency = variable_get('update_check_frequency', 1);
+  if ($frequency != 0 && $available = update_get_available(TRUE)) {
     module_load_include('inc', 'update', 'update.compare');
     $data = update_calculate_project_data($available);
     return theme('update_report', $data);
Index: update.settings.inc
===================================================================
RCS file: /cvs/drupal/drupal/modules/update/update.settings.inc,v
retrieving revision 1.3
diff -u -p -r1.3 update.settings.inc
--- update.settings.inc	20 Oct 2007 21:57:50 -0000	1.3
+++ update.settings.inc	24 Feb 2009 16:37:25 -0000
@@ -26,6 +26,7 @@ function update_settings() {
     '#title' => t('Check for updates'),
     '#default_value' => variable_get('update_check_frequency', 1),
     '#options' => array(
+      '0' => t('Check manually'),
       '1' => t('Daily'),
       '7' => t('Weekly'),
     ),