Slow down on huge Sins of solar empire maps

Hi,
I am slowly playing through all scenerios and have found I am starting to get slight slow downs on the larger end of median size scenerois when many battle fleets exists when I zoom in. I am assuming a video card rendering max out problem. System specs below, What video card has the power to handle this game when I finally get to large maps?


Playing at 1200x1900 on T240
A8n sli deluxe
opteron 185
4 megs DDR I
SLI 7800GTX
Silverston 650 watt



I was thinking one GTX285 should handle it but maybe not. It is a DX9 game from what I understand.

hahah good one
4 gigs DDR1 ram