Tomcat 4 as a service in Windows and Classpath Question

[Ernesto Echeverria <er...@integra.com.sv>]

I've recently installed Tomcat 4.1 as a service in a Windows 2000
environment.
 
In Linux, if I ever need to extend the CLASSPATH variable, I can do that
easily in the scripts provided.
 
However, I'm not clear how to do this in Windows when Tomcat was installed
as a service.
 
What is the correct way to extend CLASSPATH, and if the service needs to be
reinstalled, what would be the command in order not to loose the default
settings, plus the extra paths?
 
Thanks in Advance.