Thank you, Cornelius and others. Here's some further details that might help.
It's a iMac with a PowerPC G3 333MHZ processor, currently running OS 9.1
It has a label attached to the casing saying "Micro Touch Enabled" and the website www.microtouch.com.au. However, this website is now utilised for other purposes... from my web searches, it looks like 3M must have bought the Micro Touch company or something, and I can't find any drivers for current Mac operating systems on the 3M website.
The Mac has Touchware 5.3.2f1 installed, as well as USB Touchscreen Module and USB Touchscreen Shim. It has a little utility called Micro Cal, which looks like it's set up for a U1.2.0 Capacitive.
I'd like to install Mac OSX 10.3 on this G3 and run a Filemaker Pro database in a kiosk mode. My worry is that when I install OSX, the modules/drivers for the touch screen will be lost and the touch-screen will cease working!
What I really need, I think, is a driver for the USB capacitive touch screen sensor...
My web searches have so far turned up nothing positive - perhaps I'm trying to do the impossible!
Anyone have any ideas?