It is possible for a hack to compromise Windows Updates but I don't know of any examples where that has happened. When WU says that updates are complete I recommend checking one more time just to be sure, since some updates trigger the need for others.
There are several sites online that keep track of all of the available updates and even make it possible to more easily download them:
http://www.windowsupdatesdownloader.com ... Lists.aspxhttp://www.windows-update-checker.com/http://www.overclock.net/t/1587577/wind ... -telemetryThere are also community made update packs that make it easier to fully update a newly installed system as well as to integrate updates into the installation media:
http://forums.mydigitallife.info/thread ... stribution