OK, a second attempt to install Windows Vista 5342 on Boot Camp on a Mac mini failed in the same way as the first attempt. Here's the error text that appears after Vista Setup restarts and tries to continue Setup:
So I'm giving up for now... looks like only Windows XP SP-2 is supported (and I have no need to run THAT on my Mac... I have Windows PCs).Windows Boot Manager
A series error is preventing Windows from starting correctly. To try to fix the problem insert your Windows installation disc and restart your computer. Click View System Recovery Options (Advanced) and then run Startup Repair.
If you do not have this disc, contact your system administrator or computer manufacturer for assistance.
File: \Windows\system32\winload.exe
Status: 0xc0000225
Info: The selected entry could not be loaded because the application is missing or corrupt.
ENTER=Continue ESC=Exit