Joe- as near as I can tell the devices are fairly generic. Although there must be some tiny difference between units, try an inexpensive one. I have not tried this brand, but its probably as good as any:
http://www.amazon.com/Multi-purpose-...s=usb+isolator
Its under $40 plus shipping.
The primary value of an isolator is to break ground loops. If that isn't a problem you are having they don't help. There "might" be some value in dust collection static interference with USB. The isolator should not introduce any new problems if it doesn't help. There are no drivers or anything. To the system it just appears as "cable".
Which USB lines need them? The ones that are part of a ground loop. What the isolator does is break the connection and stop circulating ground currents. How do you determine which ones those are? Either a clamp on ammeter which reads currents under about 10 amps full scale. If you have ground loops it will be showing current in the ground and usb cables that conceptually has none. A second method is to check for differential ground voltages. If current is flowing in ground wires, the resistance of the wires generates a voltage which can be measured with a plain-jane ac voltmeter. If you are seeing a difference in ground voltage from one point in a ground system to another when the equipment is running over about 50 milli volts, you have clear evidence of a ground loop. By 500mv you have enough ground differential to mess up USB.
I am accused of providing too much information. I will stop there-
Let us know what your experience is!
D
"The best thing about building something new is either you succeed or learn something. Its a win-win situation."
--Greg Westbrook