GOG.com is giving away Dungeon Keeper for FREE this weekend only. All you need to do is sign up and then click on it and you'll get a copy, DRM-free, to use and download anywhere. Dungeon Keeper 2 is also $1.49 currently.
This is a great opportunity if you don't have either game, or if vanilla DK1 doesn't work on your computer (doesn't for me so I have to use Keeper FX).