Mike McB’s Spyware Cleanup is a good series to read through, to learn just how messed up a Windows system can get and some of the tools to use when (not if) you’re in the same situation.
Mike, you’ve got more patience than I do. When I was shown the family PC in similar condition a few months back, I did similar work for a few days. Then I gave up. I checked on the backups, reformatted the disk and reinstalled everything from scratch.