Difficult to say for sure whether you will get decent framerates, it will vary from game to game and vary within each game. You should bear in mind that you are at the low end of minimum specs and that usually means the game is barely playable imo.
Are you sure you have a 4890? If you do have a 4890 this is a better card than a 4850. You need to post back if it's not a 4890 and tell us what card you have at the moment and what PSU you have (4850's suck some juice so you need a good PSU to deal with that).
The higher the native resolution i.e. 1440x990<1650x1080<1900x1080 the less frames you get with a given graphics card as a rule. A 4890 could handle 1900x1080 adequately, but you really need to upgrade your CPU (and probably mobo and PSU too).