Start with the Deployment Status on the Monitoring node. It will give you an overview about success and failures states with a high level description. Examine client logs if that status is not sufficient (U*.log, ScanAgent.log, WUAHandler.log (%windir%\CCM\Logs)
and %windir%\WindowsUpdate.log).
Torsten Meringer | http://www.mssccmfaq.de