Under Ubuntu - plug the camera in and see what happens. There is a very good chance it will just work automagically
The same should be true of knoppix.
Chances are you'll get a popup dialog asking if you want to transfer your photos over (Y/n). have fun.
If your camera has multiple modes, you could try setting "PTP" if nothing happens under "normal" mode.
In general, linux sees most cameras a an external storage device with the vfat file system. With the 2.4.xx kernels you would have to mount the camera as if it were a usb drive, and you had a bit of a job finding the usb device it got asigned to. Under the 2.6 kernels it is all handled for you.
It dosn't matter which usb port you use.