I did it. I finally bought a new computer and switched from Windows XP to a dual-boot system (Win7+Linux Mint 12).
Unfortunately I had to realize that neither Windows 7 nor Linux Mint 12 do support the zoom-feature of the Logitech QuickCam Orbit Sphere AF.
Since Logitech does not offer new drivers and software for Win 7 (so far for that model), I can not use the whole Webcam as I wish.
Without the zoom-feature it looks like one sits a few meters away from the computer - absolutely not a good experience to work with that hardware.
I already tried out guvcview and am able to manage a lot of settings except the zoom-feature.
Is there a way to enable a software-zoom for the webcam?