As a passing thought, FC runs reasonably well on a 1998 Dell Pentium II 350, 128M ECC RAM, and an 8Mb nVidia TNT2 video card. Turn up the fog of war and leave the resolution at a lower setting to avoid choppy frame rates. If the performance from a Pentium 3 class machine like yours isn't up to snuff, you're either running an inadequate video card (like mine), or you have all options and resoultions cranked to their maximum settings and being fed to a 19-21" screen. Back off and the frame rate will improve.
They that can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.