I have a P4 2.3 with 768 Mb RAM and nvidia 5700LE with 128Mb graphics card. All graphic options enabled, Antialiasing 8x, Anisotropic 8x and 16bpp color mode and 3840 x 1024 it runs around 20 fps. I ordered a new graphics card (nvidia 6800 with 512 Mb and I think that new FPS about 30-40 ...) But you can adjust quality setting for more performance.
And you have 3840 x 1024 pixels, you can adjust zoom obviously at your preference, no problem with this, I have a 45" diagonal and is very inmersive .