"would do me pretty good with medium-high settings, "
Nope: the e2200 hasn't enough horses to run FSX where you would like it: At 2.2 gig you will be pulling your hair out and swearing that FSX totally sucks! Even the quads are pushing it: I'm hanging in, too, as I my personal answer is moving up to the i7, with an nVidia 285 gpu.
My system is still good, after two years, but I'm running the TripleHead2Go, so it makes the gpu work pretty hard, and there are times - like full overcast, thunderstorms, plus traffic - when I simply have to turn some of it down.
Your 2.2 isn't going to give you what you want, and a different gpu isn't going to give you a big enough edge to offset that cpu.
Water-cooled i7-2600K@4.9gig, ASUS P8P67 B3 DeLuxe; EVGA GTX580; 8gig Corsair Vengeance C8@1600; Win 7-64; TH2G w/3x19" Viewsonic VA926; Homebuilt airliner-style yoke and pedals; 6-pack throttle quadrant; TrackIR5 & EZCA; No blurries