FSX running out of memory

Hello people, have not been here for a while. My PC, specs are Gigabyte UD7 MOBO, 980 Phenom clocked to 4.1, 16gig 1866Hz RAM, Gainward 680GTX.(Virtual memory on PC is set to its highest), 2 500gig WD SATA-3 HDs, 2 Asus 24" monitors 2ms response, set to 1920x1080. Running Windows 7 Ultimate 64bit. Not running in RAID, not sure how to!!!
When running FSX this message (FSX ran out of available memory, adjust graphics settings and restart) appears pretty regular. Settings on game are on medium on most and medium to high on others, the FPS I get can fall to 8, but hangs around the 35 or so mark. Anti-aliasing is at 2x, other settings are low. Will only run one monitor to any effect!
I have lots of add ons, FS Global 2008, Ultimate terrain, Ground Environment, Flight Environment, FSX Traffic, Just Flight photo scenery for England. There is a lot I know, I would have thought that the card I have would cope well. (I had 3 Gainward 88000GTXs in SLi, ran FSX not so good).
I guess the latest 690 would perform better, but by what margin? Would the performance gain outweigh the huge cost of one of these cards? SSDs are too expensive for the storage available at the moment. Is there a card to supersede the 690? I got the 680 and a couple of weeks later the 690 came out!
Crysis plays really well with everything maxxed out, never drops below 40fps, regularly sits at 75fps (Explosions are nice and the water looks really good).
I know that FSX is unhappy with SLi, so there is no point in 2 680s when I could just get a 690 (runs 2 680GPUs).
I upgraded my PC recently but was wanting it to play FSX really well, but only plays it OK.
Not sure which way to go, would appreciate a shove in the right direction chaps!!

 

strewth.. it lives..

Seen quite a few people having problems with the very very latest nvidia drivers and win7 sp1..

You know.. I'd have a good look in my bios settings and just check there isn't some strange "aperture" setting.. debian64 gave me trouble for 4 years with that on an nvidia card and driver.. but error vanished with ati.. go figure

 

Hiya, thank you for your replies, drivers are the latest, (had the same problem with older drivers too). BIOS is not too different from standard, not too keen on changing too much. Hmmm....