Saab, Evo, Thanks for the replies.
I checked out all of that as much as I could in the time available, but drew a blank - I couldn't make the b u g g e r work.
I think you're right - the 11g machine should have dropped back to 11b. There was obviously a carrier (or whatever) there, hence the signal strength, and I too believe that it was just a wrong setting somewhere, but damned if I could find it and make the machines talk to each other, even though they had a connection. With a bit more time I think I could have - I certainly wanted to, but other priorites stepped in.
I wanted to pursue it for the technical exercise, but as I said, the machine in question was a gift, it had to depart, and it's now about 800km away, permanently - somewhat out of range of my network, methinks. And it won't be used on a wireless network, so the problem has solved itself. Sort of
I have heard of occasional equipment compatibility problems within a supposed "standard"

. I'm wondering if this was an example, and am sincerely hoping that it is not repeated in my friend's new gear when I attempt to set it up for him.
AA