Windows Update failed on my Windows 7 PC, and I got really stuck

Cannot Run Windows Update on a Windows 7 PC?

I tried to update an a Windows 7 PC, and I got this message:

windows update cannot currently check for updates, because the service is not running. you may need to restart your computer.

I found the above article through an article resp. a comment on answers.microsoft.com . The official answers were not really helpful at all, a reinstallation was not a serious option for me.
I proceeded as suggested in the above article, basically:

• stopping the Windows Update services through services.msc,
• deleting everything below C:WindowsSoftwareDistribution (yes!),
• restarting the Windows Update services through services.msc,
• starting the Windows Update on the Control Panel again.

And everything was fine.

I had the Service Pack 1 ISO image downloaded and burnt on a DVD, but the setup.exe from the DVD pointed me to the same problem as above.