Hey Tony, here are two quick resources for you to consider.

First, if you just want to spawn external processes, e.g. to fire up
Excel, then you can use the OSProcess package.  I know it works on Unix,
I think it works on Windows, and I think it does *not* work on MacOS. 
But you can look into it and find out for sure.

Second, there is a swiki page on deploying applications in Squeak.  It
should have a variety of info that will help you, and it would also be a
nice place for you to brain-dump anything extra you learn from the
process.

	"FAQ: Distributing Squeak Programs"
	http://minnow.cc.gatech.edu/squeak/3563


In general, I think you will find it pretty easy to "port" to new
platforms using Squeak.  In a couple of different groups at Georgia
Tech,  I have experienced for years the joy of cross-platform programs
that just work.  It's important because there are major users of a large
variety of operating systems here! 


Lex