Have you tried downloading the tutorials for RA 2008 yet? If so you probably got an error. The reason is that the files are trying to replace 'read only' files found in your Revit install directory. Here's how to workaround it:
1. Download files
2. Extract to a different folder than the default
You could then overwrite the help file this was intending to replace but you may not want to. The previous file has the link to the site where these help files are supposed to be kept and updated.
It's unfortunate. The developement team could have avoided this issue by a simple test, trying it.