Google now lets you controll its update mechanism via Windows Group Policy, allowing network administrators to specify which Google applications can be installed and how they should be updated. You can select from one of three update options: automatically, manually, or not at all. Administrators can also control how frequently Google Update checks for software updates. If your operating doesn't include a policy editor (Windows XP Home, Windows Vista Home), edit the Registry directly. Just create the following key: HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Google\Update
and add two DWORD values: AutoUpdateCheckPeriodMinutes - auto-update check interval (for example: 1440 to check for updates once a day)
DisableAutoUpdateChecksCheckboxValue - 1 (if you want to disable the auto-updater; 0, if you want to enable it)
Mac users are able to change how often update checks occur or disable update checks all together. See the Managing updates in Google Update Engine Help Center article for details.