Asset/license inventory?

I just started at a law firm as the “computer guy”. They have 50+ users in 3 offices, and no real record of who has what for hardware and software. Inventory and licensing control is going to be a major project if I have to do it by hand. Is there software out there, preferably inexpensive (the IS budget is pretty skimpy), that will “survey” the network and find out what hardware and/or software is in use? My previous job used NetCensus, which was okay, but I think it’s pretty expensive.Any ideas would be appreciated!