zipper hit the nail on the head.
If an non-partitioned drive suddenly has a problem, the chances are you will loose everything stored on it.
A partitioned drive should give you the opportunity to rescue important data (which should be stored on a non-system partition anyway).
Also, partitioning allows more ease of use and arrangement of programs.
@meega
Assigns? Why not simply create a batch file that assigns the relevant disks when needed? No need to clutter up memory with assign commands that aren't used all the time :-)