Sean,
I am using a USB to Serial convertor to operate the CAT between my FT-920 and a program called MixW V2.0. I was forced into trying the USB because I had IRQ conflicts between the comport for my TNC and CAT when both were operated from the MixW program. (I have run out of serial port IRQ options.) I orderred a low cost model from
www.iogear.com that sells for 39 bux and it works fine on my Win98SE system. It only has a DB9 connector, but they are easy to adapt to DB25 if needed. If I add more seial devices in the future, I will go this direction again...