The replacement [1] replacement [2] video card [3] finally arrived! Woot!
The good: It's the right card!
The bad: It was not going into graphics mode when I run X [4].
The ugly: It took a few hours, but I finally got it working. It seems that when I tried the previous video card, the configuration was overwritten, and it took some gentle persuasion with a large hammer to straighten it out.
So now it's time to send back the wrong card, and relax now that this adventure is over.