If your playing at 1080p and with high/medium settings that's what you'll get with your current setup.
Try downloading the latest drivers from amd or/and lowering the resolution or settings, plus that cpu is really weak.
As you can see the 6850(which is a better card) at 1280x1024 really struggles with 31 fps on medal of honor, my advice is to lower to 720p (1280x720) and turn off some settings like MSAA or SSAO or stay at medium settings, and like someone suggested see if you can oc the cpu and also the 7750 with overdrive or msi afterburn you might gain a few fps boost.
Sorry for the long reply i got busy all of a sudden
So i saw a video in youtube with the hd7750 playing assassins creed revelations.
He turned all graphics settings to the max and was playing smoothly he is using 1366x768 resolution..
I have the assassins creed revelation same reolution but lower graphics settings but i am experiencing some mini lag.