Changing DX10 preview has resolved the issue whereby Intel HD would always be used. However, if I disable DX10 preview, it uses the Nvidia GPU, an thus, black screen.
Now to solve the mystery of the black screen. I'm pretty sure this GT550m could run this at game on High settings pretty well. Intel HD doesn't do a bad job of playing it at medium to be honest, but obviously I want more from the game and my hardware.
Not a chance in a million.
It might be old, but it's somehow more demanding than Crysis.