Music:
get jpg cover art from anywhere....name it "folder.jpg" literally, and place it in the related folder.
my music/green day/american idiot/folder.jpg
to view the album art just change your view in My Music on XBMC to icons, or big icons.....all skins support this, think "the orbs" does a really nice job in displaying cover art
Video:
same thing as above, except just have one large movie directory, no subfolders, and instead of renaming the jpg to folder.jpg, rename it to the exact name of the file and change the extension from jpg to tbn
The Matrix.avi
The Matrix.tbn
WIth video you will be able to click on the poster art (a on controller) and it will play the movie. BUt with music, clicking a on the album art will just open the folder to see each indiviual song, if you want to play the whole album then click y (not sure what it is for the remote)
hope this helps
J_guzzler