I’d extremely recommend this network inventory –
http://download.cnet.com/Total-Network-Inventory/3000-2085_4-10623789.html
Total Network Inventory 3 is a useful solution for personal computer and other network asset audit and software inventory. Thanks to this very efficient network inventory tool, you will not need to carry out a manual inventory. Windows, Mac OS X and Linux-based systems can be scanned without pre-installed agents.
