FS9 upgrade: Geforce 430GT OR GTS 250?

hello,i am wanting to replace my underachieving ATI card with a proper Nvidia card. my choices for a low budget video card(s) are the following:Nvidia GeForce 430 GT:http://www.newegg.co...2-067-_-ProductNvidia GeForce GTS 250:http://www.newegg.co...rce%20GTS%20250i am wanting very high performance because i am tired of passive stuttering and textures not loading fast enough. right now, i get 20~30 FPS average with my ATI card w/high settingsso my question is, which of these cards stands out in performance and can give a good 40~50 FPS average. also overclocking the video card will not be a problem for me, since it will be very easy.system specs:-OS:win vista 32-bit-RAM: 2GB-screen resolution: 1024X1280-CPU: AMD Athlon 64 X2 dual core @ 2.9Ghz