Ahhhh...here's the Windows Vista SP1 installation screen I was looking for

Stages 1 and 2 took a combined 40.11 minutes. Stage three ended at 51.14 minutes.
What did I do differently than before?
Hmmph. I turned off Windows Live OneCare completely — both the firewall and the AV/Spyware components. The installation completed successfully. Go figure.
BTW: EVERYTHING is a lot faster with SP1. Everything.
And, here’s more confirmation that I’m golden:

One thing that’s really interesting…when you look at the graphic above in larger view, you’ll see that I’ve highlighted the Windows Experience Index. It was 4.5 prior to installing Windows Vista SP1. As you can see, Windows Vista SP1 somehow improved by number my a point.