Windows Update Fail. Consumer Rights in the UK ?

I did a clean install of W7 Professional a couple of days ago.
For the record, I have used the same disc on this same laptop previously with success.
After this instal, I repeatedly ran Windows Update to capture all relevant fixes, SPs etc.

It reached installing SP1, but only a few KBs after that, I got an error.
I followed Microsoft's recommended 'Fix It' instructions, read several online forum threads, phones MS support, used MS live chat.

2 days later, my WU still does not work.

Microsoft's stance, is that my purchase of W7 is only covered by warranty/support for 90 days after purchase.

I wonder how this would stand with the UK's SOGA, where is states that any product must last a 'reasonable' length of time.
Is 90 days 'reasonable' for an OS ?

I realize that in many IT situations, the infinite combinations of hardware, software and customizations on user's machine, make a good case for 'whos fault it is'.
However, this is a Sony Vaio, clean install with a formatted HDD.
Surely W7 should be 'fit for purpose' and should still work for at least a year or 2 !!??

Has anyone got any insight as to legal case involving things such as this ?
I know you will laugh, but I was thinking small claims court. (wish me luck).

Yes, all activated - but good to check

Ok, so I appreciate the effort in trying to fix my problem, but ...

The post wasn't really intended on seeking a fix.
I was more raising the issue of how someone can sell us shoddy goods and walk away free after 90 days.
If I buy an OS, I would expect it to at least install and update, without me spending several days until 3am googling until my eyes bleed.