I believe you just need to trust the computer on your iOS device when prompted and then use image capture. If that doesn't seem to work, you might find the device in finder and then copy the DCIM folder.
I had this problem on my PowerBook a while back and solved it with PhotoSync on both the laptop and my iPhone, but the PPC version requires Leopard. If you are on Tiger, you might have to use a different computer to put them on a USB drive, or on a cloud service that you can access from a browser on both devices.