Not sure if troll thread. or actually serious
but if you are serious. then the hd 4000 is just an integrated chip and the gt 640 is a bit faster than it.. however not by that much.. recently intel has been making some good integrated gpu's and the hd4000 can easily be overclocked to perform better than the gt 640 or so ive been told
personally i dont think an intergrated chip can out perform a dedicated full length graphics card the GT640 would definitely be a better investment