I’ve created a folder directory tree template to organize my working hard drives, and I should have done it a long time ago! Now my numerous drives are all the same layout system, they are easy to navigate, my projects won’t be a nightmare to organize at the end (or to figure out what is where if I need to revisit the project) and they will be easy to archive. And I can apply the template to each new hard drive.
Anyway, I thought I would share it and hopefully it is useful. (I’m on a Mac and I use FCPS, Pro Tools, and Photoshop, but you can sub in the names/icons of the programs you use- and customize it! It is still a work in progress, but a good start).
it is here:
4shared - free file sharing and storage - share folder - My 4shared (http://www.4shared.com/dir/6567484/f52aa5de/sharing.html)

While I enjoy your breakdown and organization, I find it easier for me to maintain and then archive my projects if I keep all associated files for the session in one main folder, and then sub folders within the project folder. (IE) Project folder/video/audio/graphics.
I average about 20 TV commercial video edits, and around 60 VO sessions a month, so It just makes it easier to backup & restore if the whole project is in one place rather than spread out.

All the Best!

Actually, i think that IS the layout. i do audio projects, video projects, graphics projects and photo projects. each 'area' is separate, and in that area is an 'active project' folder (or actually three 'projects in progress' folders) that contains all elements for that project, broken down into sub folders. when finished, it all goes into the 'archives' area in the single project folder. then that area is open for the next project. i personally can't imagine tackling more than three projects at once, so i stopped the active folders there...

I have taken to changing the system settings in FCP (all of the scratch drive locations) every time I edit. It is a supreme hassle, but it keeps everything for each project in one main folder and means I don't have to worry about re-connecting clips or any of that when I go to archive or restore a project.