Haha, I'm currently playing Prototype 2 on an Nvidia card (460) and the performance is far better than I was expecting after the bitching I saw online.
You're lucky then. The game ran at 60FPS, but looking at it you'd never be able to tell. Always looked between 20 and 30. Then we have the crashing that would randomly occur. Best compliment I can give that game - it autosaves better than most. Even with how awful the port was, I still played the shit out of it.
I'll try lowering the AA to normal, but there's already a ton of aliasing.