There are two issues here: the region code and the content protection.
The region code is enforced by the DVD drive itself. The drive firmware can usually be hacked, and many drives have an easy hardware mod (cut 1 PCB track, etc) which removed region coding. It is after all in the interests of DVD drive manufacturers to not make users' life hard.
Up to about 2002 the region code in PC drives was enforced by the player software. One cannot buy such drives now, though I guess secondhand ones should be on Ebay. I used to have one, a Pioneer; got rid of it because it would not play most writeable DVDs.
The content protection is something else; it is a straight data encryption system and the decoding is done by software running in the player (or in the case of a PC, by the main processor). This was always going to be cracked eventually, simply because the machine is open to running debugging code, etc. This is what de-css does. Hi definition DVDs have already been cracked, despite having a much stronger scheme - again because the "system" is open.
Sony own big chunks of the music etc business and they go to extra trouble to prevent copying. That's why we have the protected memory sticks, the fancy firmware in their DVD drives, etc. I would never buy a Sony laptop now; for this reason and also because "Sony=quality" has beed dead for about 10 years - nowadays Sony stuff is crap quality Chinese contract made stuff unless you buy near the top of the price range.