Replying to self!
I decided to try once more. Followed the instructions in Yossarin's posting No.39 in this thread, but as I'm using Vista I had to use "Programs & Features" to uninstall.
Note - if you don't click the "Publisher" column you will not see all the Nokia programs. Delete them all.
As for C:\Windows\Inf I ran a search for "Nokia" and this found over 70 files, all of which I deleted even though "Nokia" wasn't in the file name.
I then rebooted, and no sign of PC Suite in the picking lists.
Ran the PC Suite I had previously downloaded Nokia_PC_Suite_rel_7_0_7_0_eng_web.exe but nothing happened.
Downloaded it again, this time to the suggested folder in my "Downloads" (I am the Administrator) and ran it from the saved file immediately.
Still no sign of PC suite in the picking lists!!
I then plugged in my phone to its charger (PC seemed to pick it up better this time than running on battery on previous attempts). Plugged any old USB cable into the phone (switched on) before plugging into the PC, as per other peoples' suggestions.
Immediately the drivers were discovered as in my posting above, PC Suite booted up, and now appears in the picking lists on the Start Menu.
Phew - and no registry fiddles either!
May I respectfully suggest Nokia put this as a fix where it is more readily visible to all?
Now to try and add a second phone!