The Updater category should be available in Adobe Reader XI (and X) Preferences in a normal installation.
See http://helpx.adobe.com/acrobat/kb/reader-acrobat-updater-settings.html.
But, Updater can be disabled in Windows registry or in an enterprise deployment.
If you are familiar with editing Windows registry, which is a delicate operation, you can verify the following registry entry: HKEY_LOCAL_MACHINE : SOFTWARE : Policies : Adobe : Acrobat Reader : 11.0 : FeatureLockDown. If there ia a registry entry named bUpdater and its DWORD value is 0, Updater is disabled and Adobe Reader automatic updates won't happen. If you delete bUpdater registry entry or change its value to 1 you will have the Updater category in Preferences.
If you don't want to deal with Windows registry you can try to uninstall Adobe Reader, run Cleaner tool, and then install Adobe Reader again.
You can download Cleaner tool from Adobe Labs: http://labs.adobe.com/downloads/acrobatcleaner.html
Adobe Reader and Acrobat Cleaner Tool
The Adobe Reader and Acrobat Cleaner Tool removes a standalone
installation of Reader or Acrobat, including any preferences and
settings that may be preserved during a standard program uninstall.