The key once it is fu'd is to get completely installed. Right now 9.2 or 9.2 probably have their uninstaller as well at 50 other things in x86 and Program Data, etc.
The best thing you can do -- I had to do this -- is to install damned near every program AC, lol. If you can get an older version on without its saying there is a newer version on, hence installing the whole shebang, i.e. SQL, then uninstalling with Revo or Uninstaller, so that all of the registry entries are uninstalled. Generally, you have to go through to the end and get another error message and do it again.
