I have an Intel 2.4 Ghz, ATI x1600 256mb, with
512 RAM.
I can run GWX with the 16km mod, the normal harbour traffic, and with modest AA and AF. I get really good frames. Like 20 or more. I have a page file thats 2.5 gigs and SH3 uses about 1.5 - 1.6 gigs when its running. I have no issues, only slightly slow TC around a harbour.
You can definitely run it better than me.