A reliable plugin for monitoring windows-based systems?

Well, the subject says it all - I am looking for a reliable plugin to monitor windows-based systems (similar to NSClient++). I need to monitor some metrics, that are not accessible by snmp (or, rather, it is impractical to access them through snmp). The problem with NSClient++ is extremely sparse documentation, so when it comes to doing something even remotely non-standard, it is trial-and-error all the way.Besides that, some of its modules are declared “broken” by the author, which doesn’t add to my confidence. Eventually this nagios installation is going to be the only monitoring system used in the network and having an unreliable, underdocumented way to check metrics on windows-based systems is unacceptable.

So I am asking, does anyone know of a better plugin for monitoring remote windows-based (server 2003/server 2008) systems?

AFAIK NSCLIENT is the only one.