I just purchased the game on Steam today, and am having the same flickering border issue.
I've tried setting the multisample to every different setting but nothing has worked. (0,2,4,8)
I was using the beta Nvidia driver, 290.53, but even updating to the latest, 295.51 didn't work. I might try the last official version but will lose the massive performance increase in Skyrim.
Also I have both DLC, but not sure if that matters or not.
On a lighter note, at least I don't have the heavy stutter issue I had with EU3 :happy:
Windows 7x64 Home Premium
Nvidia GeForce GTX 460 768mb
Intel Core 2 Quad Q8200@2.33Ghz
8GB RAM
Dxdiag Attached