Jerky framerates

[optimizer]

Ok. Here we go again. I am sure that somewhere this has already been asked. But help me know what I need to change. Railworks 3 is running very jerky. I had problems before the upgrade but now it is worse. According to the info given, I have hardware that should run it OK. But something is not right. So here is what I have. I realize it is not new, so what do I need?

ASUS M3N78 Pro motherboard
AMD Quadcore 9500 Processor
3 gig of ram ( I am limited to 3 gig because I am running 32 bit Vista)
Nvidia GeForce 9400GT (1 gig)

Which is more important in my case, more ram or a better video card or everything new? IF new video, what is the minimum upgrade to get?
And can a person really have good enough hardware so that there is absolutely no hesitation in the frame rates at all?
Thanks in advance for your helpful response.

[barnez]

I'd lean towards videocard (and consider Win7 64bit for more RAM)

As for a specific model card - nvidia GTX 560/ 560ti appears good if you can swing the $$$. Next step down would be the GTX 460/ 470 series or the GTX 550ti series

-barnez

[harryadkins]

Some people have had success with uninstalling Steam and Railworks. Then, when Steam reinstalls Railworks, the program does an initial setup based on your computer's specs. After the reinstall, it's easier to "tweak" the basic settings RW determines best for your computer.

Harry