Digital BW, The Print

This question may be rendered moot in Photoshop CS as according to 
Evening's introduction you can have a "live historgram" running while 
you use curves.  As I understand it, you will be able to see the 
impact of any curves ajustment on the histogram in real time.

The bad news, at least for some of us, is that it looks like CS 
requires a Pentium III processor.  I have a II with plenty of memory 
that works just fine with PS 7.

Steve