Thanks for your comments. I found out quite by chance that part of the problem seemed to have been that I had the webcam attached to a cheap USB hub which was then attached to the Linux (mandriva) box. When I connected the webcam directly to the computer, I could see the dkms-gspcav1 module being loaded in syslog. Using kopete, I could get a fuzzy type of picture. The lines in syslog said that there was a problem with a) light frequency and b) a memory leak. So there has been some improvement, but I am not there quite yet
Thanks for your help