I had the same problem with my previous XP notebook, which had USB ports but no serial port.
(My current notebook PC has a serial port along with the USB ports.
) I was surprised to find out from my experience that even XP does not include a compatible driver for a serial-to-USB adapter - I had to install it from the included driver CD before XP would recognize the adapter.
(Ouch, you spent quite a few coins on an old PC. I got my current notebook for a little over $300.
)