You can do Dual Graphics with that card and that APU by following this guide:
http://www.youtube.com/watch?v=NFAMmTDu_H0
But AMD recommends connecting the monitor to the card rather than the MB port. Also, for best results, you'll want to use 2 or 4 sticks of RAM so you have the advantage of dual channel speed. If you haven't already bought the memory, get 1866MHZ RAM. The on-die GPU uses system memory for its VRAM. So it needs the fastest possible memory to keep up with the HD 6670's VRAM.
I had the same APU and card. It works fine, but I don't think you'll be impressed with the dual graphics. I wasn't. I ended up using the HD 6670 as a discrete card.