I have a similar rig as the OP
AMD 955 Black OC to 3.8 Ghz
2 Asus 6850s Crossfire OC with MSI Afterburner 930 Mhz GPU 1125 Mhz RAM
8 Gigs Ram
Asus 990 FX MB
I have excellent frame rates in game. My PC is a pretty solid gaming rig. I average between 40 and 65 FPS most places in game. If I go into Lion’s Arch my system tanks though I go down to about 25 FPS.
I’m pretty sure it is a CPU bottleneck, but overall I’m really happy with the performance. Before catalyst 12.8 and the new Crossfire profiles it really sucked. My guess is that the OP has not upgraded his drives or Crossfire profiles as this made about a 15-20 FPS increase everywhere in game for me. Lion’s Arch was pretty much a slideshow before the driver update.