That's excellent news!
You fell victim to Windows 7's most common error code/corruption. Now, whilst I cannot absolutely prove this, my 5 years of experience working Windows Update issues tells me very strongly that this is a software bug. Whilst most other errors have a motly assortment of causes - various different hardware failures, power failures whilst installing updates, etc. etc., this one is different: although the actual updates vary, it's very distinctive in that it a) only a small number of updates are corrupt, b) large parts of those updates are corrupt, and everything's almost always matched up, c) it's always perfectly neat.
Hardware failure doesn't cause neatness, it causes the worst sort of disorder imaginable. I don't think this is that. No, I believe it's something quite different.
My best guess is that there's a failure condition somewhere in the installation logic which the rollback mechanism doesn't understand. When it occurs, the rollback does not get properly initiated. This leaves a neat partial installation, and would easily create the pattern observed.
I don't know, it's a complete guess, but I do believe this to be a software bug of some sort, but alas, after years of searching I have never been able to pin it down exactly. What you need to take away from this is threefold:
a) you didn't cause it/do anything wrong
b) the chance of it re-occuring is very small
c) there is no evidence of hardware failure here
So not all bad, eh? :)
Take care, it's been an absolute pleasure to work with you!