I ran into the message (paraphrased) that "this software isn't meant for your OS" so, not trusting the compatability mode for complex installs, I took a look at where in the install scripting the OS was being sensed.
I used the distributions disk that came with the QCP9000. I copied it to a spare HD volume and modified the setup.ini file's [OS64] section in the "Elevated" folder from MaxVersion=6.0.9000 to MaxVersion=7.0.0000 and installed from the modified file set.
I may have made another, similar change to one of the other cfg or ini files - sorry but I don't recall. Anyway, after doing this the install proceed normally for me and now, under 64Bit Windows 7 Ultimate I have QuickCam and drivers
working fine. This installation also works fine with Skype and MSN Messenger video calls.