Here is the best tweak guide ever for Skyrim. Koroush Ghazi is the master when it comes to tweak guides. http://www.geforce.com/Optimize/Guides/the-elder-scrolls-v-skyrim-tweak-guide
Having his own site http://www.tweakguides.com/
, he now provides the same service to all of us through Nvidia's site.
The first page gives you the requirements for the game. The rest of the guide will inform you how to get the most enjoyable playing experience out of the game for your particular equipment.