iBook doesn't recognize iSight

Hello to all. I have just bought an external iSight camera (second-hand) from another Mac user who no longer needs it, as I am in no financial status to buy a new computer yet. It came in its box and I have the purchase receipt (original) and all the accessories. The previous owner used it only twice, as he bought a new machine with an integrated iSight.

I have been having trouble as my iBook just won't recognize it. If it is plugged to the Firewire port (I followed the instructions in the manual), my System Profiler won't even detect the FW port (no info message). I have iChat with AIM, and also use Skype. I have tried different FW cables (known good), the camera light turns to green and makes the whirling noise, etc. but none of the apps recognize the device (black screen, green screen in iMovie). I have researched for help on the Apple tech supp pages, googled the problem, seen EZ Jim's pages, etc, and so far nothing seems to work. I haven't yet tried resetting the PRAM as I don't know that is an option for this problem and my specific system profile. Please, EZ Jim or anyone, help. I live far from family and friends and would love to be able to video chat with them. Thanks in advance...