You really should give GFI LANguard Network Security Scanner 3.0 a try you can download it here @ http://download.com.com/3000-2092-10...ml?tag=lst-0-1

GFI LANguard Network Security Scanner (LNSS) is a freeware tool to audit network security and proactively secure it. LNSS scans entire networks from a 'hacker's' perspective, and analyses machines for open ports, shares, security alerts/vulnerabilities, service pack level, installed hotfixes and other NETBIOS information such as hostname, logged on user name, users etc. It does OS detection, password strength testing and detects registry issues.
Hope this helps.