In my original post I gave the XML required to associate windows computer objects and health service watcher objects - but I didn't walk through exactly how to set this all up.  I've updated the post with a walkthrough of how to put all the pieces together - hopefully a bit more useful!

http://blogs.msdn.com/steverac/archive/2008/10/17/grouping-windows-computer-objects-and-associated-health-service-watcher-object.aspx