[G4] Best use for the 2nd HD

[Raymond E. Hardy]

My newly installed internal 2nd HD (Seagate-120 gig), installed with the
helpful list recommendations, is working well. Thanks!!

First thoughts about the best use for this new drive suggest that I should
try to put all my "document" files on this "slave" drive -i.e., all my
audio, picture, Word, QuickBooks, etc. with the OS and Application files
remaining on the 1st drive.

Once again I've got a lot of "newby" questions and will value any
suggestions.
Would you copy the documents to the 2nd drive then simply "select" the
originals on 1st drive and delete them? - hoping to improve performance.
If this is the best idea, can the Applications be set up to seamlessly
access and save files to the 2nd drive?
Should I usually start the desired application by selecting a document from
the 2nd drive? 
Best regards,
Ray