Apparently, my choice to block iTunes from infesting my startup programs with qttask.exe is what caused it to not install its bundled version of Quicktime. This time, my spyware blocker just notified me that it had been added, rather than asking me whether I wanted it added, and when I checked, I had Quicktime again.
This just makes me hate qttask.exe all the more, in case theer was any doubt.