Sorry for long delay - we have a plenty lot of work with RAdmin 3.0, and freeware network utilities lack our time. But for now all is ok, and i just update all 3 utility - Advanced IP scanner, Advanced Port scanner and our new Advanced LAN Scanner.
NetBIOS names problem solved - it occures only on Windows XP without Service Pack 1 and is Windows XP problem. We implement customization option that allow program to run slowly, but return correct results.
Also, speed was greatly increased - more than 1000 port are scanned per second! (100 ms timeout, 128 threads / or 200 ms timeout 256 threads).
If you have any suggestions - feel free to contact us.