See what Creative has to say about it...
My cam (Logitech Traveler) used to do that, but my CPU was too slow at the time, so I expected it. Now if I can just get it not to trip the bus...
Does the image get faster if you drop the resolution...like from 640*480 to 320*240 or 160*120? I would think you should be able to run at 640*480 and be OK... Does this happen in the camera's software package, or in anothers (like NetMeeting/Yahoo!, if you have tried them)?
Does the device also show under the USB Controllers as well as an Imaging Device, and does it have the correct name?
Perhaps contact the USB card's manufacturer, as it may have problems with your specific camera.
I'm guessing that this is your only USB device... so you can't tell me if other devices work there...
Have you tried checking out the USBMan website? Lots of USB info there...
http://www.usbman.com . You might be able to find something there. Please let me know.