Yes you can copy dvd-recorder recorded disc using your pc. I always capture old tapes directly to pc so I don't need a recorder but my dad also has a sony dvd-recorder and I copied some of his discs. I just copied the content to my hdd and burned it with nero or imgburn. But depending on the record mode of the dvd-recorder the files on the disc can be different. In standard mode you get a normal VIDEO_TS folder but in some different modes the recorder creates a different folder with different files.

Btw, I think if you capture your tapes with your PDI card and encode them yourself the results will be much better than a dvd-recorder can produce.