Hello Grashuepfer
If your "Creative WebCam Pro" is one of the newer ones that supports the "UVC" standard for USB webcams, you can use it with your PowerBook by updating to to the latest version of Tiger (Mac OS X 10.4.10.) Support for all UVC webcams is built into OS X 10.4.9 and later with no need for additional software.
If your "Creative WebCam Pro" is NOT a "UVC" model, try the iChatUSBCam and appropriate "macam" driver that
Pismo 900 recommends above.
EZ
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Jim
PowerBook 1.67 GHz Mac OS X (10.4.10) G5 DP 1.8 External iSight