Leigh B. , May 15, 2011; 03:22 p.m.
Active displays (computers and such) are done in primaries (RGB).
Printing is done in secondaries (CMYK). The K (black) was added because you can't get a good clean black by mixing Cyan, Magenta, and Yellow inks.
So the answer to your question depends on the client's application. I would supply both versions of each image.
You can set up two directories on the CD, one for Display and one for Print.