See our site http://home.wanadoo.nl/scripting , which contains
a lot of scripts for making an inventory of software and hardware.

Those scripts contains mechanism to create dynamic and/or historical logs.
To prevent you doesn't catch them all you can reboot (= all user will be
logged off) server and after each loggin on you can get the wanted
information.
Greetings.

btw: symbol on our homepage has been linked to related http://kixtart.org topic.