Yeah the latest knoppix contains kernel above 2.4.22 which handles usb a lot (even much much better) usb then before.
So for usb issues it wouldn't hurt to use the latest kernel....

And for the tip about gqcam : I've encountered people before who had troubles with xawtv but when using gqcam they could use the webcam.
Search the knoppix site on 'gqcam' and 'webcam' . I think you will encounter similarities... .