GSA-4081B in a USB external enclosure

As the subject says, I have a GSA-4081B that I used happily inside a PC for a while. Now I’ve put it inside a USB external enclosure and Windows XP does not recognize it.

Is anyone using this drive in an external USB enclosure? If so, I’d like to know the version of your firmware and your brand of enclosure. I have never upgraded the firmware of the 4081B; before going to the trouble of installing the drive inside a computer once again, I would like to know if using the latest firmware would make it work with USB.

Thanks for any help.