1 drive for samples (now at 15gig somehow...)
contains a folder called 'samples' and a folder called 'original-libraries' and i move stuff into categories from 'original-libraries' to subfolders of samples like 'samples/drum-hits/hihats/closed-loose/hat13.wav' or whatever

system drive contains the software

then there are a couple of huge drives containing all the projects and related audio each project has its own folder containing everything it needs to playback successfully (including bounces of all synths and outboard effects used) and usually a collection of mp3 bounces. each session is saved with several version numbers in case i need to go back to an older idea. usually the project folder gets moved to a 'completed-projects' directory when we are done with it for the time being.

finally there is a folder called 'completed-tracks' containing the most up to date 16 bit 44.1k aif of each project for putting onto CD's or whatever.

and that's that...