Well, there's bad news and good news. The bad news is that fiddling with that rather user-unfriendly driver package download achieved nothing. Having loaded the apparently appropriate drivers, the install still hung at "Press any key ........".
The good news is that when I made Win 7 Install do a format of the selected partition (an option which should be more obvious during the install process, in my opinion) the install proceeded without any problems. I have no idea why this made a difference. I had previously "Custom" installed over a working XP partition, and on a clean re-formatted partition (using Acronis Disk Director). I had assumed that the Install would automatically format an active partition (unless you were doing an upgrade), or at least make it obvious that a format was needed - as did previous versions of Windows. Apparently this is not so.
However, all's well that ends well.