courtesy of MCoreD.
Requirements
— iTunes for Windows - http://www.itunes.com/
— iTunes Store Account - you can easily register for an account using your CC for free. You only need your CC for authentication. Otherwise, you can use http://www.tunecore.com/freealbum for a free gift which will create you an iTunes Store Account.
— iTSfv beta version from - http://itsfv.sourceforge.net/
Install iTunes and iTSfv
Load iTSfv
Automatic method
1. Browse an album in iTunes Store. Click on the first track in the album.
2. In iTSfv, using Selected Tracks menu, click "Export iTunes Store track Artwork…"
Manual method
In iTSfv, using Tools menu, click "iTunes Artwork Grabber". This window should now appear:
It will do its thing and try prompting you to save the Artwork. (*.jpg is the default)