Nice setup, did you try to get the 2600K to 5GHz though?
My current system is a GTS250(810/2052/1250) with an e8400@4.2GHz, and 2G of PC2-9600, with a wd raptor 150. Its running XP-32. In crowded areas I drop down to 24fps, even when running with middle-quality settings and 1024x768

I'm thinking of upgrading my system with a setup similar to yours, so could you reply with some info:
When you enabled SLI, did you notice any additional increase in input latency, or micro-stuttering? Have vsync/triple-buffering enabled? What do you have your "Maximum pre-rendered frames" set to? Do you notice any (even tiny amount of) stuttering when characters models are being loaded from the HDD?