EMCO Network Software Scanner is a handy management tool which can collect details on the applications installed across your network.
The program doesn't require any special clients to be installed on your network PCs for it to run, and it doesn't use WMI. You will need to provide it with the credentials for administrative access (so you'll need an administrator account on each system), but with that in hand all you need to do is point EMCO Network Software Scanner at a group of PCs (or let it scan everything) and leave the program to work.
Once the process is complete then you'll see the installed applications on each system, and their update status. So if some computers are missing a few key updates then it'll be very easy to spot.
The reports are also saved into a database for easy access later. And if you run the scan again a month later (for example), it's easy to compare the new results with the previous scan to see which applications have been added or uninstalled.
And although it's free, EMCO Network Software Scanner 1.0 doesn't have any annoying restrictions on the size of network it'll scan: it'll work happily on networks of thousands of computers.