video capture device not detected

I am using a Sony digital camcorder and when I try to capture video using a
USB cable, I get the following message:
A video capture device was not detected. Verify that a device is turned on
and connected properly, and then try again.
When using a firewire cable, the camera is found right away. This is fine
for home use because my computer has a firewire port, but for the classroom
that wants to use Movie Maker, those computers only have USB.
What can I do?
Mike O.