I recall changing my display through Settings.  If I remember my Av500 originally had Data, Info and System, as well as Pictures, Playlists, System, Video.  The latter had what looked like image or background files.  
My current list shows:
Data
Info
Music
Pictures
Playlists
Recycled
Spoken
System
Video
I created Spoken folder for my lecture notes, and I created subfolders in Pictures, Video, etc.
Somewhere on the Archos site you can download the original folder contents.  Have a look.  If I find it in next few minutes, will post it here.
...
Just found it at 
ftp://support.archos.com/AV500/Data (this has fonts and manuals)
Info
Music
Pictures
Playlists
System (this has jpgs)
Video