I have a dual core high end PC with 4 GB of RAM and a GTS 8800 nVidia card. I have just refreshed the drivers for it today. I am running Windows 7.
I am playing the game at 1280x900 and performance is awful. I am playing on the initial levels (borg and asteroid) and the game simply lags and jerks continuously. If I lower the resolution to ridiculously low
Perhaps you solved your issue regarding your GTS8800, but it very understandable that you can't play in high settings. The card is obsolete if you like playing in the new generation MMO's like STO, Guild Wars 2, The Secret War and Star Wars: The Old Republic.
E.G. if you like playing Ultra settings in The Secret War recommend is to get GTX550 or Radeon HD7700 or better. GTS250 1GB will do, but you have to lower some settings. Recommodation: upgrade Windows tot 64-bit so you can use 8GB, 32-bit OS has a limitation up to 4GB only!