You wont need a video card in the server to host games, I use to host a sauerbraten server, it just runs some code in a terminal and listens on a certain port, doesn't need anything graphical. Infact you would even be able to run game servers with no video card.
The parts should be the same, ram, mobo, CPU and HHD. Anything else you need is extra (Assuming that the case has a PSU). CD-Drive maybe, but you could just FTP files to it.