Verified answer

Is it installed, or isn't it???

Try downloading the Vista X64 device drivers, if available, for your specific Model Number, from Logitech's website.

Still stuck? Call Logitech's Tech Support line, and complain!

Go to there website. They have the drivers you want. It does also help if you would mention the model of the webcam. Getting an answer without that info is a worthless question to ask on here.