I realize I'm a little late replying to this post, but hopefully I can be of some help to those of you like me who are a little late at reading this post.
As far as an driver update for the Samsung SD-612 DVD-ROM compatible with WinBLOWS XP... it does not exist. Thanks to the "wonderful" people at Samsung who stopped supporting this and many other products of theirs. The SD-612 is simply NOT compatable with XP and I'm sorry to say, there is no solution.
At least my Piece of Sh** Samsung DVD came with my computer when I purchased it so I didn't flush all that money down the toilet per say. Look on the bright side though! You've got 2 CD-ROMS.... hmmmm.. ;(