does the pc-105 have a memory stick 'reader' (or whatever it is called)? if it does, just insert the memory stick, turn on the camera, hit play, and when you want to capture a still, just press the "photo" button.
you will then need a memory stick 'reader' in your computer. Or you can just download the DV video into your computer thru a firewire connection, and capture the stills using your favorite video edition software.
mm.. that wasn't very helpful, was it? :)