GTX upgrade for FSX

I run FS9 in XP and have a large collection of sceneries and aircraft, both payware and freeware. I run a triple monitor system as advocated by Alex Reid with GoFlight throttle quadrant, Saitek ProFlight rudder pedals, and CH Eclipse yoke. I use FSUIPC for almost all the calibrations. The system runs well, graphics are very good and I get stutters only when AI is cranked up very high. It is all extremely stable. Linked into it through a LAN I have ASA, Radar Control, and vasFMC. I prefer turboprops to jets and fly the old Dreamwings Fokker 50 a lot of the time. This aircraft was made for FS2000 I think. I have modified Espen Oijordsbakken's superb custom made panel by replacing his gauges with ISG gauges, including an FMS, to produce an aeroplane which is exceptionally realistic to fly and is stable. But...the notion that FSX is better continues to nag. FS9 is such an old program now. The more I read, the more I think. On my dedicated flightsim PC I have a 2nd HDD which has FSX and W7 Home Premium x64 installed on separate partitions. I have flown FSX just once with a default Cessna and it seemed okay but wondered what all the fuss was about. Now, I wonder if future addon investments should be for FSX. However, I doubt if my current system will do it justice. Basically it is built around a Q9650 running at 3GHz. I have GTX cards (a GTX260, core216 oc, 896MB - this runs 2 screens; also a GTX250 for the 3rd screen). I have 4GB fast paired DDR2 but I realise XP cannot utilise it all. My questions - and thanks for sticking with me this far!1. Would a simple upgrade of my GTX260 be enough to run FSX with complex FSX addons without stutters, say >27fps? I do not mind winding down AI traffic and autogen.2. I am addicted to FSNav. I know this will not run in FSX. Is there anything comparable with a moving map display which I can use in FSX?3. Does anyone know if my existing triple monitor scheme (Alex Reid) can be used in FSX? I have had conflicting advice about this. Obviously, if it cannot then that will make it almost impossible to run FSX and FS9 off the same monitors. The only solution would be to run FSX on the centre monitor only.Whatever I decide I intend to keep my FS9 system as is at present. I have cloned the HDD. Sorry for the long post and apologies if some of it is not strictly on topic here.Thanks.