How big of an upgrade in performance will I see in a dual video card and a physics accelerator?

To mention that I am an online, frequent gamer. I just purchased a Dell XPS 630 and went with dual nVidia GeForce 8800 GT 512MB plus an AGEIA PhysX physics accelerator card. I have the Quad-Core Q6600 (8 MB, 2.4) as my processor. Does anyone have any ideas of what kind of performance I can expect?|||You should be getting amazing, top of the notch performance, (I.E. if you play Crysis, with max settings but AA off you should get at least 50 fps which is saying a lot)