Hi Scott -
Even with a single drive, I will partition it. I will set-up one for the os, one or more for programs, and a smaller one for data. I like to do this mostly for the smaller block size(forgot the correct terminology). If a program is 'core' to the operation of the PC, I will install it into the OS drive. Otherwise, it would get installed on a program drive. This same thought can be applied to multiple hardware drives.