The funny thing is, that most computers made from 2004-2014 (with more than 2gb RAM, and even Intel graphics) will 99% likley run Em4. But if you wanna run mods like Manhattan mods that are big and maybe not 100% optimized, and also maybe run Em5 one day, you're going to have to put a little more money into a graphics card and in some cases a somewhat decent CPU to "future proof" your pc a little bit. My suggestion would be an i3 or i5, and R7 250/R7 260 or Nvidia 750, these graphics card are fairly low end cheap but it would suprise me if they didnt run Em4 and Manhattan mod and they are still 100x better than integrated graphics such as Intel. But obviously the more money you can put into your computer the more "future proof" you're gonna be. My 2 cents..