And I had kept an old notebook somewhere in the attic (a Pentium 3 machine) just because it still had a RS232 port on it. My two recent notebooks only have USB ports, so go figure.
After I had calmed down ;-) I made a bid and did win it for nine US Dollars. Lucky, I know, I saw other usb-rs232 cables had been sold for more than twice that sum. Anyway, I waited patiently and after four days the package with the cable arrived.
The next day (yes, quite amazingly I could wait!) I connected the cable to my PC and plugged it into my 3MX. Nothing happened, except for a message in a window that asked me to install the driver. No problem, the package included a small CD with plenty of drivers on it. And no manual. I tried all drivers and nothing worked. I finally found a solution and put up a separate page with the driver that worked for me as a service to fellow Psion users.

Let me come right away to the end conclusion: this is a great invention! Now I can connect both my Psion MX machines to any PC with a USB port. That is my two desktop PC's and my two notebooks. Great!