Hi,
The two old machines work fine for all other apps that I can test, including YouTube.
I was using them because they have serial ports and I wanted to develop a serial application. I can't bear the pain of trying to get them to work, so I have purchased a cheap PCI express card for my main machine with 2 x serial and 1 x parallel ports. At £25/30€ it's worth being able to use the infinitely more powerful 64-bit machine.
Also, this one is in my front room and the others are in the attic 8^)
Thanks for the help anyway.