Needed to open a big range of ports on Windows Firewall on one of my web boxes. Via the GUI you can only do one port at a time. But run this at the command prompt to add a range:
FOR /L %I IN (5001,1,5201) DO netsh firewall add portopening TCP %I "Passive FTP"%I
This opens ports 5001 to 5201, and names them 'Passive FTP'.
Found this here.
Oh, takes time, like a port or two a second, so if you have a wide range it's going to take some time.