Software Search App.

I’m looking for a software search applicaton that will go out and search all my computers (approx 600)and let me know what software is running on them. As my tech’s go to users workstations, they are reporting seeing more and more freeware and shareware install on them. I work for a state agency that doesn’t allow any “outside” apps to be installed. At present, we use Landesk, but it doesn’t seem to be very accurate. I’m curious if anyone has seen such an app.
Thanks,
Steve