Memory Nvidia Geforce 7950 gx2

I have a Dell Dimension 9200 Dual Core 6700, 2GB RAM, HD in RAID 0 configuration (FSX on C: virtual memory on D: , Audigy X-FI Music, Nvidia Geforce 9750 GX2 and I have to say that I'm satisfied about my experience on FSX.Following the most part of the tweak suggestions red here (great site and forum!!!! Thanks for that) with the exception of the texture reduction, I normally have, flying with Boeing 737, 15-20 FPS in the most crowded airports and flying at low level on bigger city, 22-30 FPS at FL below 6000 feets, 35 FPS (my set limit frames)over 6000 feets.Another info regarding my conf: following some posts i have made a test installing all the sceneries on D:, but i am returned back not having any improvement of performances using two different drives (probably due to my blocksize on the drives? but i dont know how to change it).Usually i start FSX after FSAutostart utility and have all sliders at max or very high (Autogen on dense, Traffic roads and ships 60%, AI Traffic 80%).4x AA and 16x AF set on the card, trilinear filter on FSX.Only issue I have a random error starting FSX: after some loading time i return on the Desktop without any message or with a message related an attempt of FSX.exe to write in a read memory area. Not understanding why, but immediately restarting again FSX normally the problem disappears.And now my doubt about my Nvidia card that should have 1GB memory: I have used some utilities to check it(i.e Silvia Lite XI, memstatus 2.50) and they report to me only 512 Mb memory. I would like to understand if this is normal (may be due to the conf of the card having 2 cards on the same slot) or if its possible that i have a problem with that.Thanks in advance for your supportCiao and happy flightP.S. Sorry for previous post in wrong forum