Upgarding from GT 220

Hey,

I've been flying with FSX for a couple of months and when I use 'bare' Flight Simulator, without any addons it is ok, but the more payware addons I use, the more stutters and FPS drops I get. I know it is caused by my very average computer which is:

CPU: Intel Core i3 530 3,00 GhZ

Mainboard: Gigabyte H55-S2H

GPU: NVIDIA GeForce GT220 1GB

RAM: 4 GB DDR3

Power Supply: Silentium Deus G1 500W

Windows 7 64 Bit

I know that the weakest component is my video card so I would like to improve it. The options I have considered so far are: GTX 560 1 GB or GTX 650 (or GTX 650Ti) 1GB.

Are these card good for my computer?

Please take into consideration my average CPU which I would also like to overclock a bit (up to 3.6 GhZ I think would be good).

I am not a very demanding simmer I suppose - what I want is FSX to run quite smoothly with some payware planes (like PMDG 747, Aerosoft Airbus X) with payware sceneries on just average settings (I don't want to move my sliders on max - an avrerage settings are sufficient for me). I don't use programs like REX, UTX etc.

So my question is, will improving my GPU let my FPS go up a bit? For now, using PMDG 747 and German Airport 3 from Aerosoft I can get approximately 12-16 FPS when I am on the ground.

Cheers