if I understand our friends White Hat Mike & Brian, would clear WU history, the next restart would have the computer begin from the beginning with all available updates -- similar to just having purchased a brand new computer.
Not really. The download history is located in the C:\Windows\SoftwareDistribution\DataStore folder. If you clean that folder (empty it) or rename it (it'll be recreated), you'll just lose the ability to see via the Windows Update panel what updates you installed. You won't have to re-download any of them because Windows still knows which updates are installed and which aren't. As for the Download folder, it'll only force Windows to re-download the updates that were pending for an install, which is a good thing because often updates that stays in that folder for too long will have their file corrupted or dissapear and the update won't be able to install.
In other words, there's nothing wrong in deleting the content of renaming the Download and DataStore folders. It's often done for Windows Update troubleshooting.