First... the app. does not work on XP, because XP does not have the problem of missing AlbumArt on all tracks.
When the app. is loaded for the first time, it finds the default location for the dat file.
The dat file location should not be changed; I have planed to remove this option, because you are not the first one to ask about this field. So leave this field as it is :)
The rest should be straight forward, but ask if you have any further questions.
If you have more than one HTPC with Vista, the app. must be installed on each one of them.