Model: PCRW4816K/20 etc
Operating System: Windows XP (Note: might work with other versions of this os.)
It worked fine for me on my PCRW4861K/20, but if you have any reservations, or your computer is likely to crash in the five or so minutes it takes, THEN DON'T DO IT. You will end up with a scrap drive.
Docs are included in the Zip. The models covered by this updater is huge, so read those to see if your drive is covered.