depending on the screen size on which version ie single or multi-player your gonna run medium for single player. low on multiplayer @1920/1080 maybe if your lucky medium @1280/720 but really you will be stretching it some to stay over 30 on a 1080p screen on anything near medium settings. the 550ti is basically a gtx 260 rebadged and dx11 architecture added. so dont expect stunning performance.
nice. much better option, your will get medium high on sp. medium low on multiplayer... you want 60 fos minimum on multiplayer to stay competitive... truest me its better to drop the settings than look good dying.