The only settings i have in my video card is is with nvidia inspector and it is set exactly to this thread http://forum.avsim.net/topic/324786-nvidia-configuration-guide-inspector-2xxxx-drivers-version-20-explanations-of-all-settings/
As I've started reading it, I came around that red warning about AA not working in DX10, being "slow and buggy", but that's how AA looks like here, under DX10, see the screenshot, no antialiasing problems at all. I've set it as suggested in that thread, but didn't make any difference.
The issue is, that guide was last updated 1 year ago, and drivers have been improved, and many tweaks has been discovered to make DX10 usable.
The only thing I find very useful in the nVidia inspector, is the included frame rate limiter (with recent drivers), which works well, so you can leave "Unlimited" in FSX, which is faster, and limit it with the driver, which is the correct way of doing it. This allows a much smoother flight.
But that's besides the point. Can you just try with *some* of the most critical sliders turned down, to see if it makes any difference ? Like autogen, scenery complexity and scenery radius, and without too much road/boats traffic ?