Currently, the HD 7660D on my A10 APU is sufficient for running most of my games though I'm looking for a bit of a boost. My motherboard is an Asus F2A85-M and my PSU is 500W, though I don't think power would be too much of an issue when dealing with a card that doesn't need a 6-pin connector.
On another note, is it worth Crossfiring a GDDR5 6670 with the A10? I've heard some bugs happening with people who've went with it as well as the fact that it apparently does worse on some games than the 6670 alone.
What is your budget? Just forget Hybrid Crossfire - might as well get a decent gaming card. Your PSU could easily support an HD 7850 - can play all games on High at 1080p.