Just bought a new computer with two internal drives. I plan to use the second drive, which is partitioned into drives "E" and "F" exclusively for  Poser. Program and runtimes on "E" drive. PZ3s, backgrounds and renders on "F" with additional renders on an external drive. Currently I am running Poser on an external "H" drive with PZ3s and renders on "J" drive.

I understand that Poser Runtimes can be dragged and dropped from drive to drive wihout any problems even if the drive letter is different. Hence I can move runtimes from "H" to the new drive "E" without any problems.

PZ3s can also be moved in the same manner. However, if a PZ3 points to a background that was previously on "J" drive but has been moved to "F" drive then Poser will not be able to find it. If that is true, would I be better off naming the 2nd partition "J" so that Poser can find the backgrounds and information that was previously on the external "J" drive? But I might then have trouble if I need to use both "J" drives at the same time. Or should I just leave all the PZ3s and renders on the original "J" drive?

Hope that is not too confusing. Any advice would be appreciated. Thanks

I would leave well enough alone.  Attempting to similarly name 2 drives will force your OS to rename them automatically, or choke in the process. 

Personally, I would just open the PZ3 in a text editor and find/replace all the J drive references to F.