Interesting, I have the same processor as your former, Cat (the Phenom II X4) and I cap out around 9k for extreme and about 12k for medium. My card is a GTX 470. I've been thinking about upgrading after the new year, but I'll probably stick with AMD. I know it's not "Gamer Elite" to choose an AMD processor, but I like the money I save.
By the way, the game looks fantastic on high settings