It finished installing, and gave a functional desktop at the end. With no network card (despite the installer using it earlier..).

So now I'm installing the mobo drivers.

EDIT: that worked, seems to have gotten the machine online. Now Windows Update beckons, with hundreds of patches since 2008.

But first, I'm going to redo the base install on the real (new) target drive: a "WD Black 1TB", in place of the scrap drive I used for testing the install.

Later.. much.

Thanks again, guys!