Map the drives which hold the mp3's
You will get something like E-drive on 'Basement Computer'
For the database system...
Maybe you could use Musicmatch Jukebox.
This program contains a library where you put in all of your mp3's.
You can fill the database manually by selecting a drive and its directory..
When you've spreaded your mp3's along several harddisks on several machines.
You are going to fill the database by just putting in all files from the disks on the network..
Maybe not the ideal software to use, but I know it works, and you are able to select the songs from the database which you want to play...
I hope this helps you out !