When I said "brings my PC to its knees" I was referring to it with most of the settings turned up. I use an AMD 965, 8GB DDR2 and a GTX 560ti 2GB. Some of the settings on the highest actually look worse, so I keep those on medium. Still, I can get as low as 15-19 frame rates during large battles.
Strange because I have almost the same system and it runs fine with most settings turned up. Only with heavy-AI missions is when my CPU has trouble keeping up; but with most normal SP/Co-op missions I don't have any issues. Might see if you can OC that proc to ~4GHz
It might be the OC. The Takistan map (open desert) runs fine, but Cherrussia in an area with lots of trees kills my frame rates. I am also playing with ACE, which seems to reduce frame rates a little.
On my GTX 260, I used to get 50 frame rates in small towns/open desert with low-medium settings, but the moment I looked at a few trees my frame rates would drop to 15 or so.
The game also gets my GPU hotter than any other game I own, even more than BF3. I have not tried Rise of Flight or Cliffs of Dover yet though. RoF uses all 2GB of my video RAM, so I suspect it will be quite demanding.