Nvidia card owners :
http://www.steamgames.com/nvidia/
ATI card owners :
http://www.steampowered.com/ati_offer1a/
Team Fortress 2 free for all :
http://store.steampowered.com/app/440/
NASA's Moonbase Alpha :
http://store.steampowered.com/app/39000/
Portal 1 :
http://store.steampowered.com/app/400/
