Well, on the second infection, removal was even simpler than the first time. I just killed the process and ran Hijack This, and found that it didn't reinstall the BHO or even the Run entry in the registry. Perhaps there were traces left behind that fooled the installer.
I'll have to revert to a pre-infection snapshot and try again. --
To ISPs: Leave our ports alone! If I want ports blocked, I'll do it myself, thank you.