Tracking users’ activity in WP-powered intranet

hi

i’m using WP as a cms to build the website of an architecture bureau. There will be an intranet section in the site (i’ll probably use the post levels plugins for that) . Problemo is the following:
administrator of the site wants to be able to track (intranet’s) users’ activity (user ID, login time, accessed & downloaded files)…
somebody knows how to do that?
i heard of Performancing Metrics in the forum. Is this tool able to do that, or is there a better way to manage that (like a plugin)?
thanx in advance!