The first problem was the at the Ricoh combo drive in that PC has been playing up for a while and does not always read CDs. This is a drive that cost about £150 a few years back when mere mortals were not able to write DVDs. So I swapped in an old CD drive. That was refusing to boot too until I worked out that the jumper was set wrong on the back. After that I got my first sight of the Ubuntu start-up screen. The excitement was short-lived as it was followed by a blank screen and a dead keyboard.
There may be an issue with the motherboard (Asus A7N266-VM) that uses an nVidia chipset. I'll investigate that angle. Meanwhile I'm downloading the latest version of Ubuntu to try out. If that doesn't work then I may investigate Knoppix and Mepis, both of which I have seen at the LUG. It may just take me a while to download them. I'm still waiting for ntl to upgrade my broadband to 2Mb.