If you checked and there are no failed updates then you should be alright. I have my updates set to notify but don't download or install so I can see what updates I am getting. Yes I think if you had a power bump it would corrupt the update and you would have run windows update again.
Windows Update is a service provided by Microsoft that provides updates for the Microsoft Windows operating system and its installed components, including Internet Explorer. An optional feature disables access to Windows Update, enabling instead access to Microsoft Update, an expanded version of the service which provides updates not just for the operating system and Internet Explorer, but also for other Microsoft software running under Windows, such as Microsoft Office, Windows Live applications, and Microsoft Expression Studio. Updates are normally provided over an Internet connection, although there is provision for updates to be installed on computers without an Internet connection.
There are different kinds of updates. Security updates or critical updates protect against vulnerabilities to malware and security exploits. Other updates correct errors that aren't related to security, or enhance functionality. http://blog.teesupport.com/