Originally Posted by u.v.bunny

I only learned recently that if you own any version of The Witcher or The Witcher 2 (on steam, other digital sites or retail) you can use the key that came with it to redeem a free copy of that game on GOG.

I used the CD key from my steam copy of The Witcher to add it to my GOG account. Maybe I'm the only one that didn't know about this, but if anyone needs it, the page is here:

http://www.gog.com/witcher2/backup