I have a client that is pitching to a board with his software product
that works in with other software.  We believe just taking a small
piece of the pie and working in with other systems well is technically
superior than trying to completely replace a system that already works
fine.

Replacing the system means new training to staff, hours of
implementation time etc. etc..

I know this, but what your task is, is to find a quote from someone
like Steve Jobs or Bill Gates that can back it up.

I remember seeing an article on Steve Jobs saying that the future of
software is modular or "component-based" software.  Where say, it is
cheaper to license a function to implement in software than write that
function yourself.  So effectively, you have software at the macro
level which inter-plugs to make a solution.

In summary - I need a quote for the presentation, ASAP.

I couldn't find anything very apt from Steve Jobs or Bill Gates.

Here are a couple of quotes that might be helpful:

======================================================================

General industry consensus is that the ultimate goal is to have
component-based systems capable of operating in distributed
heterogeneous computing environments. Loosely bound and highly
configurable components will be able to accommodate continuous changes
such as the rapid creation and destruction of virtual enterprises.

--Richard Barnwell, Architect 
Software 2000, Inc. 
(June, 1995)

Stevens Institute of Technology
http://www.cs.stevens-tech.edu/~badri/cs765/dom.htm

======================================================================

"We've reached the point of diminishing returns with shrinkwrapped
software. The challenge is to deliver the last ten percent of what
people need to do, and that means modularity," said Jonathan Seybold,
publisher of the Seybold Reports and host of the conference."

NextWorld
http://www.simson.net/nextworld/NextWorld_Extra/92.11.Nov.NWE/92.11.Nov.NWExtra04.html

======================================================================

I like the second comment, it's brilliant (and true).
But to a non-technical person it might not carry the weight that I
need (whereas the name of any fortune 500 CEO might).

I spent a couple of hours trying to answer this question myself
through google searching, but couldn't.

Here's a "legacy" quote from Bill Gates:

"It has been a long time in coming, but the Industrial Revolution of
software is finally upon us," said Bill Gates, chairman and CEO of
Microsoft. "Specialization of resources, standards for interchangeable
parts, and streamlined assembly tools have been used in other
industries for hundreds of years to speed the development of highly
complex products. Despite their ubiquity, application of these
concepts to the modern software industry is just beginning. Visual
Basic 5.0 advances this trend considerably by finally making it easy
for millions of developers to create and assemble high-performance,
broadly reusable ActiveX components."

http://www.components-online.com/Version98-4/OldNews.htm

More recently Bill has moved the discussion beyond a mere espousal of
why components are good.  The .Net umbrella covers many initiatives,
but taking the role of "components" for the Web-enabled applications
(and devices) are something Microsoft likes to call "Web services". 
Here's a short snippet from a recent presentation shepherded by Bill
that makes this point:

BILL GATES: One thing that I mentioned is very important is XML Web
services. This is essentially the infrastructure that's necessary to
fulfill the promises of the late '90s, and early in this decade about
what the Internet would do. ... And every developer here should be
thinking about how they provide Web services, or how their application
can connect up and use the Web services that will get built.

http://www.microsoft.com/billgates/speeches/2003/03-19mdc.asp

If you just wanted to have a concise quote from Bill Gates, I'd
probably take the first one and drop the last sentence which mentions
VB 5.  After all the concept of modularity as a virtue is pretty old,
actually being present in essence in Dijkstra's "Go To Statement
Considered Harmful":

http://www.acm.org/classics/oct95/

regards, mathtalk-ga

If you are trying to "up" the buzzword density in your presentation,
throw in the phrase "best of breed", a close relative of "best
practices" that (as applied to software packages) implies the best
system can be created by combining the best functional components.

regards, mathtalk-ga