GTX 260 - Q9550 Poor performance with flight simulator

Hi, i just built a new computer with Q9550, 8Gb ram, GTX 260 Nvidia with windows vista ultimate x64 installed.
I used to play flight simulator on a core 2 duo processor with 2 Gb of ram and i was getting reasonable graphics on XP 32 bits.
However now that i try to play the game on my new computer, the graphics are so poor. And if i adjust the engine, memory and shaders to 3/4 using smart doctor, i get a message that my system has ran out of memory.

Does anyone know how to solve or fix this problem?
thanks

i mean by poor graphics at the fact that first, the edge of objects such as aircrafts look kind of square, and second while playing the game, the image is not consecutive, what i mean is that it shows one frame, and say one second later another frame, and so on to the point that the game closes and i get the message that my computer has ran out off memory. Let me ask you, why should i uninstall smart doctor utility?
thanks

^ It'll only recognize 4GB of his RAM tho.

Less than that actually, but the reason may become apparent.