I had an AMD 2200, 512MB Ram, and a much crappier video card and I still got 15-20FPS on AH... not the best system, but still ran it sufficiently.
I now have a E6300 core-duo, 2GB ram.. and a better, but still sucky, video card... 55-65FPS, at max settings.
Basically that system should work fine for AH, but you'll probably have to stick with 512 textures.. not the end of the world.
And YES AH benefits from dual core.
Good luck.