Hmmm... I want to add, for most files, you can move them whereever you want that makes sense inside the six main directories of your poser library (Camera, Lights, Hands, Character, Pose, Props).  For example, if you want to put your clothing textures with the clothes themselves you can do that, just move the folder.  Also you can make any subfolders you want, so if you want to group all the clothes together for example, make a subfolder called "clothes" under Character, and put all the desired folders in it.  I also subdivide further under clothes by model (V4, M4, M3, etc), and further under that by clothing type.

The only folders you CANNOT move anything in without breaking things immediatly are /textures and /geometry under /runtime, and /data under MyLibrary.  Don't touch those.  As always, making a backup before you make changes is highly recommended.