End of the debate: Microsoft SMB can work over tcp/445 period, over and out.

The many discussions you're facing if you don't want to open ports udp/137, udp/138 and tcp/139 in your firewalls end here:

http://technet.microsoft.com/en-us/library/cc940063.aspx

Direct hosting over TCP/IP uses TCP port 445 instead of the NetBIOS session TCP port 139.

Direct hosting has been available since Windows 2000!

Ok, but just yesterday we have had a machine that we could not teach to use tcp/445 for SMB it always defaulted to NetBIOS over TCP/IP. Was a W2K8 R2 and has some registry corruption issue that prevented it to connect to any fileshare. Solution to that was to set the server to DHCP and then back to static, but it now only goes over 137-139.