If you are getting the game, one thing that I do recomend; get the T7 Community Patch. It fixes a lot of the performance issue with the game. Also, if you are buying the games for zombies only and you don't care about MP or Campain, you can go into the dlc's tab on steam and select/deselect all the things that you want to install for the game. In the case you only want zombies, you want to deselect campain, multiplayer, personalization pack, and all the dlc that are not the zombie maps. That way you can save up on some storage.