So this is a store bought rig? I would say at low fps and low settings you should be able to play the game. Unless you OC a bit on your CPU and GPU. Then you might be able to make it to med.
But if your res is low you might be able to play on med settings. If you had a 4 core CPU and a 400w PSU or bigger you could game with a 6870 GPU and play on high settings. Just a thought. I do wish you good luck.
6670 will run the game fine, if you disable AA it can run on high. The only concern is your CPU, I haven't seen it benchmarked for skyrim specifically, but I think it will allow you to run with at least medium.
if these are all your parts for a homebuild new rig then you're missing quite a few: