So basically until I upgrade my CPU/mobo, a new GPU would give me a few frames more around complex scenery but not much more than that. Am I correct to infer that?

Yes. At the cases when the first CPU core isn't around max load a faster CPU is useless. You already have available CPU cycles that arn't getting used to produce FPS. It's basically your GPU or a combination of the GPU and the PCIe bus that is holding you back. What chipset do you have on your mobo at the moment? Does it have PCIe 2 support? So spending money on a faster GPU should be the first priority. GTX650, GTX650ti or GTX660 are once that come in to my mind. GTX560 and 560ti would work as well. But you won't be able to utilize the power of the faster GPUs until you upgrade that old CPU of yours.

Hey guys, more or less a newbie here, just thought I'd ask some opinions:

I'm trying to put together a workable FSX rig, and its now time to upgrade my cpu/mobo from a 4 year old dinosaur to something I can squeeze some better performance out of. It looks like everyone is all about the i7's but I'm really on a tight budget and the Phenom ii x4 965BE looks like a steal for 90 bucks and 3.4ghz out the box. Now, I am definitely someone who believes on 'you get what you paid for', so is there anyone who uses it and can give me some specifics on the ups and downs on getting something like this?

 

I am currently using an Athlon 64x2 running at about 2.7ghz. On a PMDG NGX and running REXE, I get anywhere from

 

I now have such a Phenom II X4 965 (OC 3.8 GHz) which replaced an AMD 64 X2 6000+ at 3.1 Ghz. I experienced a clear improvement in performance when using FSX or other games like total war shogun 2. I use a Nvidia GT250 1 G video card.

Still my system isn't quite up to run FSX as I would like even if it's much better after the CPU upgrade. But I bought the Phenom since I'm bound top my AM2+ motherboard.