Unless the modders or Bethesda write a 64 bit version of the Skyrim exe, you won't need more RAM than that. Even with the Large Address Aware Flag on, Skyrim can only use a maximum of 4GB. Really high resolution texture packs may increase the game's video RAM requirements, but that is handled separately from system RAM, and you can only get more video RAM by upgrading your graphics card. Right now the only reason to have 16GB of RAM is if you are running certain content creation applications that can use that much. If you want to upgrade to be slightly more futureproof, go ahead, RAM prices are at rock bottom right now, but don't expect any improved performance in games. Even games that do have 64 bit versions of the exe don't use more...