If each directory has a dvdid.xml in it, and media center is set to retrieve additional info, it willl get extra metadata info, including covers for each DVD. Im not 100% sure if category is included, but there may be some kind of genre value.
Find them all pre-made here:
http://dvdxml.com/news.php
This is for Vista and W7 by the way, not sure this works with XP.
Andrew