For forum knowledge - I found a beta version of Keyspan's software for 10.7, which purported to have both 32 and 64 bit drivers in the one package. However, it stated it was only for the USA-28UX model, not my USA-28. Little to lose, I decided to install, and it works a treat! The Keyspan software detects the USA-28 adapter properly, although it only works off one serial port (number 1).

NCX now works and I can copy stuff to my Newton

JB