Question: Do not see an improvement in FPS, It seems as though there is actually a drop..
What I did: Uninstalled drivers and installed the cards. Afterwards I booted up installed drivers, and CCC had auto-enabled CFX. A window popped up to "set up" CFX, I clicked "go" and then nothing happened. Rebooted.
Result: A system with a 6850 CFX and very little increase in performance, if any. For example, I have skyrim modded up the wazzoo with shaders and larger textures, I play it at 1366x768 and got a huge drop in fps down to 10-20. With the second card installed the fps is the same.
You have to uninstall your drivers, install the second card (don't forget the crossfire cable), and re-install the drivers. Also make sure you install the latest crossfire application profile when you're done.