Should i be getting higher frame rates on my gaming rig?

That sounds about right. A pair of 5770s is about as strong as one 5850, so it looks correct, uming that's at 1920x1080 with AA (depending on game). Also, if you can tell the difference between 60 and 100FPS, you're not human because the human eye can't physically notice the difference. So, why would you even want higher framerates, they would be invisible! Your rig is great as it is, enjoy your gaming.