Network Auditing Utility Needed

I’m looking for a freeware tool that can do a simple audit of systems connected to the LAN. I need it to at least report Processor, RAM, HD info. OS and other details would be gravy. I know Zenworks etc are the ideal products to use, but that’s not possible for this project.

I’d like to be able to run the scan transparently from a server and gather a database of details by machine name (plain text, xls, access, or something like that for format).

Any recommendations?