Just to let others know, I have just done a fresh install of W7 Ultimate x64 on a brand new Kingston SSD from my original retail O/S dvd, absolutely nothing else on my drive, no programs at all.....
Had to install all updates including SP1 and NET Framework 4 etc, everything was fine, rebooted, then get a message saying Windows Update installed an update for MU Agent 7.6.7600.320
Now I also have no updates available, tried the microsoft Fixit file, installed all the KB's listed in this thread, and re-installed MU using the MU installation tool from Microsoft, stopped and restarted MU in services, and tried the windows update diagnostic tool, nothing has worked, update has now been checking for updates for 8 hours with nothing found.....