Have you tried downloading the last Boot Camp version manually and installing it and seeing if it "takes"? You also might try to download the PRIOR version and installing it manually and seeing if it still works?
Or have you tried opening the Boot Camp drivers folder and installing just those files you need?
BootCamp 3.2 - 3.3 breaks the functionality with Windows 7 at the latest patch level.
The fix has been:
- upgrading OSX to Lion
- Patch to latest release
- Go To Boot Camp Assistant
- Download Windows Support Files to Jump Drive (second option I believe it is)
- Reboot into Windows 7
- Run Setup - BootCamp 4.0 will install
- Launch Skype or MSN Messenger - ISight will magically work again!