The second time I try to integrate SSRS with MOSS, and the second time it starts with horrible failure.

Normally, when you install the SSRS SharePoint addon, you get a new section in CA, named "Reporting Services". Not in my case... Trying a repair on the addon didn't help. Uninstalling it and going back to the 2005 version didn't work. Not much left to try here, except for...

reading documentation. Since I'm more hands-on, I tend to only read documentation when the "just do it"-method fails. Microsoft's installation guide states there are 3 ways of installing this thing. For the second time, I find that only the 3rd way works. As an added bonus, the feedback is easier to intercept this way.

After the installation succeeds without exceptions, you'll notice that the "Reporting Services" section is there in CA/Application Management. From here on you can proceed as indicated by Microsoft. After that you might be able to deploy some sweet usage reports, like the one in the attached image. How to do this is for another day...