What is the right way to set the JAVA_HOME environment variable on Windows NT?

In my case it's just

set JAVA_HOME=C:JDK1.3.1

...but if you're running NT the "right" way to set this is as one of the system's User properties, which you can do via

start -> settings -> control panel -> system -> environment

then enter JAVA_HOME in the Variable box and C:JDK1.3.1 in the Value box, and click on Set.

By the way, Tomcat is one of the easiest to install pieces of software I've ever seen - but you do have to get this bit right.