The more I look at this computer, the more desperate the situation becomes! I dread to think what has happened to the COMPONENTS sub-hive. The only possible explanation I have, and the more I look, the more evidence I find for this, is that there is enormous corruption/destruction in the COMPONENTS sub-hive, a portion of the registry used almost exclusively by Windows Update. From what I can tell, every single update ever installed has become corrupt in the registry. That sort of damage cannot be repaired.
The only glimmer of hope we have is the System Update Readiness Tool (SURT). This tool is known to be very imperfect. Oftentimes it reports the error somewhere miles away from where the true source lies, e.g. here, where it reports it in the CBS key, but actually it lies in the COMPONENTS sub-hive. Also, it will often miss errors, fail to trace properly (especially here where the registry keys it relies on for tracing are corrupt), and report the true errors only after we "fix" the wild goose chase it has gone on.
This all sounds very negative, and it is. There is only one, hope, however. SURT works on the same underlying technology as Windows Update. If we can make SURT happy, even if we don't actually properly fix the problem, if we can trick it into thinking the problem is fixed, sometimes Windows Update works.
This is our final hope. I am going to be completely honest here, and say that the level of corruption you have is beyond almost everyone's ability to repair, and is certainly beyond my ability. SURT wants us to delete *everything*. It has gone on a wild goose chase again, and is asking for the few remaining fragments to be deleted, realising that they are orphaned.
The only hope left is to trust SURT, delete these last few fragments (and in doing so actually, technically, making the corruption worse), and see if Windows Update works again. It might just. If you are running almost fine with seemingly millions of corruptions, deleting 15,000 orphaned fragments may actually make things better.
Imagine this as a last ditch effort of merging every update into the RTM image, and hoping that future updates work successfully.
I will begin preparing the fix. If you are willing to take a slight risk that this may make things worse, I am willing to try our final last ditch effort for making things better.
P.S. You could try a Repair Install, but if the corruption really is this bad, I doubt very much that it will succeed. Only a Clean Install can truly fix this. If you have nothing to lose in one final last ditch effort, then I am with you. If you need this machine running, then I would suggest stopping now, and not risking pushing it over the brink, until you can Clean Install.