Thank you for that, P.Pilcher! I've had a look at the dialogue box for the magnifier and have unchecked all of the little boxes even though none of them seemed to have anything to do with the actual calling up of the service. Come to think of it, none of them seemed to be related to the switching off of the magnifier once it has appeared.... How to do that would be useful to know too because there is no "cancel" box apparent when the magnifier is present.
Thanks also for the tip about the XP code sticker - my 98 machine didn't rise to that sort of sophistication and I hadn't read what was written on the little label. Its presence would seem to support my confidence that the late owner of the machine would have done everything by the book. Should I tell ZoneAlarm to let WGA call home and give the "all clear" to Microsoft or will that allow Big Brother to set still more traps and to interfere further? I could always ban it from all future communication.... Perhaps I'm paranoid but my suspicions about these things seem to be supported by the fact that I'm not permitted to uninstall anything to do with WGA. I'd love to know where the "genuine advantage" lies for me in all of this!
Going back to the XP question, I was in fact left two more or less identical computers. This one has XP Home installed while the other has XP professional. I wonder why the switch would have been made.