@Chronobomb: Bah ...
Stop talking shit please!
Learn a bit more about SLI / CF Systems, it makes sense if your using the latest HighEnd Cards and really need 2 or three of them (like if your playing on a big fat TV or with 3 Monitors). 2 Midrange SLI Cards are slower than the next single Midrange GPU and only with luck better than the HighEnd Cards (which costs mostly less than 2-3 of the other ones and doesn't need a 1KW PSU). 1 GPU more are (with luck and hardly depends on the Game) +30% more Power. If you are unlucky, you get 0 FPS more AND you have to live with the microstuttering (or whatever it is called in english, sorry).
@DirtySancheyy: Your 8800 GT isn't the newest one, sure.
But the Bottleneck here is your CPU so you should start with upgrading your Mainboard, CPU and RAM.
After all, the Game reaches pretty fast the 2GB Limitation in bigger Maps which means it WILL running slow even on high end machines or even crash.
A good thing you should do is to reduce your Empire Tree which will cause a big FPS drop after some time, i just keep my main Fleets in there for a quick overview (Health, Enemys etc.).