Like you said in your first post Windows Genuine Advantage Validation Tool (KB892130)" won't install and this seems to be the reason why you can't install the latest updates. I have no reason to disbelieve you when you say your copy of windows is genuine but have a look.. here ...as it describes the purpose of Windows Genuine Advantage Validation Tool (KB892130)" and Windows Genuine Advantage Notification (KB905474.
There has been cases of genuine copies of windows being flagged as pirate ones and if i were you i would check... here ...first and see what it comes back with..