I've got the 1.65 Ghz CPU (and accompanying AMD 6320 GPU), 4 gigs of Ram, but I replaced the stock hard drive with a SSD.
Runs just fine, and I'm having a huge blast!
forget about anti aliasing or hires mods (like the four hundred) though.
Then again the inventory gui overlay occasionally whites out and i have ot esc the ngo back to game to make it better, but othe rthan the very rare crash. Especially given I'm on linux running this in WINE with an intel graphics chipset. I consider myself astoundingly lucky.