Why not?
The prime issue is whether the drivers can be satisfactorily loaded after the OS is in, and probably more importantly, if in fact Sony are failing to supply a workable set of drivers. It seems to me I'd be no better off if that driver install program is corrupt.
The site I'd found and the one you also pointed to seems to be the correct Sony site and clearly allows one to select Windows 7. 32 or 64. At some stage while running the executable, it then informs me the install will only run on Vista. I can't see this could be finger trouble, (at least 3 tries) or that it will change with a new install.
It was a total mental aberration not spotting that chap's suggested downloads were not for the correct model. He was wrong to suddenly change models, but we should have been on our guard as it was an open forum. That's life.
It was the plan to do as you say once I'd tested the OS on this machine. However, the OS and the Office 2010 have been updating like crazy several times a day, so I hope I don't have to go through all that again just because of a driver issue.
I'm going to restore back a bit and see if I get partial use of the keyboard back. Windows + X is a workaround I can live with.
I do feel somewhat frustrated not to be able to do things other folk seem to find routine. Hope it's bad luck and not age related brain-fade.