The tough but highly popular action-RPG Dark Souls from From Software debuted on PC nine months after its original console launch, in the summer of 2012. The aptly named Prepare To Die Edition made use of Games for Windows Live, but now players will be able to transfer over their progress to Steam.
Now the developers are letting users update their PC game to ditch GFWL functionality and use Steamworks features instead. Good news is that "the update is available now and will let players keep both Save Data and Achievements".
There's a dedicated thread at the Steam Community with instructions on how to migrate on different cases (depending on how and when you bought the game), but it seems like some users are having issues related to some custom 'fixes' for the PC game.